diff --git a/docs/CIRCUIT.md b/docs/CIRCUIT.md
index 890a1c1..1bb5da2 100644
--- a/docs/CIRCUIT.md
+++ b/docs/CIRCUIT.md
@@ -22,6 +22,7 @@ V1a part:
 | V1a | 12AX7 | p1a, g1a, k1a | |
 | R1 | 2.7 kΩ | k1a – gnd | |
 | C1 | 0.68 µF | k1a – gnd | Full cathode bypass |
+| C2 | 100 pF | p1a – k1a | V1a plate–cathode (drawing iss. 4; added D-062, was open item O8) |
 | R4 | 100 kΩ | bpA – p1a | Plate load; bpA from supply B7 |
 
 There is no junction between V1a and V1b: p1a is an internal node of B12 (the J1 junction was
@@ -253,7 +254,7 @@ Regenerate with `python3 reference/spice/spice_tools.py` after any netlist chang
 | O5 | NFB tap | 16 Ω output with the speaker load (D-059) | Feedback amount if taken from another tap |
 | O6 | Low input | Not modelled | Feature only |
 | O7 | OT half-primary orientation | Blue–White (15.36 Ω) on the pA side (V4/V5) | ±0.6 Ω winding asymmetry, about ±40 mV DC per side |
-| O8 | C2 100 pF V1a plate–cathode (drawing 2203 STD Preamp iss. 4) | Not in the netlist (found 2026-10-15) | −0.3 dB at 5 kHz, −0.7 … −0.9 dB at 10 kHz into V1b (SPICE study) |
+| O8 | C2 100 pF V1a plate–cathode | Resolved: in the netlist since D-062 | −0.3 dB at 5 kHz, −0.7 … −0.9 dB at 10 kHz into V1b (SPICE study) |
 | A1 | HT source 505 V / 100 Ω | Assumed | B+ level and sag |
 | A2 | OT values | Hammond 1750U replacement datasheet, primary inductance fitted (§3, D-023) | Power, LF/HF response, feedback |
 | A3 | Choke 5 H / 115 Ω | Hammond 194F replacement datasheet; L specified at 120 mA DC, the amp runs it at ≈ 27 mA (D-024) | Screen node dynamics, supply DC |
diff --git a/docs/DECISIONS.md b/docs/DECISIONS.md
index 3bc1df7..db5f078 100644
--- a/docs/DECISIONS.md
+++ b/docs/DECISIONS.md
@@ -1043,3 +1043,14 @@ at 0 V. Above +20 V, P = Vpk within 0.1 V (DC operating point unchanged).
 Consequences: engine diagnostic: HOT DI 0 power-amp failures at 8x and 16x; CRUNCH / DRIVE unchanged (−218 … −224 dB vs
 the previous engine), HOT differs by −35 … −37 dB. tests/data EL34 sweeps regenerated; the pentode test asserts the new
 below-cathode behaviour. SPICE references with the power amp are re-rendered.
+
+## D-062 C2 100 pF (V1a plate–cathode) added to the netlist (reference model change)
+Date: 2026-10-18 · Status: accepted (owner: "add C2 to the netlist")
+Context: the drawing (2203 STD Preamp iss. 4) shows C2 100 pF from V1a's plate to its cathode; it was missing from the
+transcription (open item O8, found 2026-10-15). SPICE study: −0.3 dB at 5 kHz, −0.7 … −0.9 dB at 10 kHz into V1b.
+Decision: `C2 p1a k1a 100p` in the netlist (B12 partition). The engine adds it to V1a's plate–cathode capacitance port
+(`cpk1a_` = Cpk + C2 in `Preamp` and `StageV1aV1b`): the same two nodes, so the parallel combination is exact.
+Consequences: DC unchanged. Every SPICE reference containing V1a is re-rendered; earlier reports are without C2.
+Also found: the standalone blocks' default supply voltages (Preamp, StageV1aV1b, StageV2aV2b, StageV2aV2bToneStack,
+PhaseInverter, PowerStage) were still the pre-D-058 values (bpA 389.35, bpX 402.34, ct 488.71, nScr 485.65 V); updated to
+CIRCUIT.md §5 (391.92, 405.00, 491.35, 488.88 V) with the block DC fixtures (the full amp sets its supplies itself).
diff --git a/docs/PROGRESS.md b/docs/PROGRESS.md
index 994b714..b89ebed 100644
--- a/docs/PROGRESS.md
+++ b/docs/PROGRESS.md
@@ -842,6 +842,13 @@ Notes:
   model) and are now rendered once more at RELTOL 1e-7 by `render_spice` (as the M3 cascade), noted in the reports. Plugin
   model check: Full 2x HOT −24.2 dB (PASS), unseen −20.8 dB, 94 first-solve failures (2 unrescued) over 28 runs, nearly all in
   the extreme validation settings (presets: 0 / 0 / 2); Half 2x HOT −18.9 dB. Presence knob jump −62.9 dB; null test 26 / 26.
+- Owner 2026-10-18: add C2 to the netlist (D-062). Plan: `C2 p1a k1a 100p`; the engine folds it into V1a's Cpk port (Cpk + C2,
+  B1234 and B12: the same nodes, exact); B12 partition; re-verify b12 (DEFAULT, VOL0.2, VOL1.0), b1234, knob jumps b12 / b1234,
+  M4 acceptance at 768 kHz and 384 kHz exact J4 + HOT, plugin model check (Full 2x), null test, CPU.
+- D-062 done. b12 / b1234 first failed on DC (≈ 0.65 %): the standalone blocks' default supplies were pre-D-058; fixed
+  (engine headers + block DC fixtures). Then: b12 DEFAULT / VOL0.2 / VOL1.0 105 / 106 / 106 PASS, b1234 119 PASS, b3 87 PASS,
+  b34 94 PASS (0 FAIL each); knob jumps b12 −55.9 dB, b1234 −39.1 … −55.1 dB, b34 −53.1 … −67.6 dB; M4 full acceptance 107
+  PASS (768 kHz and 384 kHz exact J4); HOT 20 PASS / 1 FAIL (2 rescued first-solves, as after D-061); null test 26 / 26.
 
 ## Questions for the owner
 _(Claude Code: add questions here and also ask them in the session.)_
diff --git a/engine/include/amp2203/PhaseInverter.h b/engine/include/amp2203/PhaseInverter.h
index 6789bac..d249d18 100644
--- a/engine/include/amp2203/PhaseInverter.h
+++ b/engine/include/amp2203/PhaseInverter.h
@@ -26,7 +26,7 @@ namespace amp2203 {
 /// (g3b−k3, p3b−k3). Presence is smoothed (SPEC §6.2); R_th4 follows the preamp's knobs.
 class PhaseInverter {
 public:
-    static constexpr double kSupplyBpX = 402.335999;  // CIRCUIT.md §5
+    static constexpr double kSupplyBpX = 404.998185;  // CIRCUIT.md §5
     static constexpr int kParamUpdateInterval = 32;
     static constexpr int kNodes = 8, kElements = 18, kRootPorts = 4;
 
diff --git a/engine/include/amp2203/PowerStage.h b/engine/include/amp2203/PowerStage.h
index ab78be0..b6f8f9a 100644
--- a/engine/include/amp2203/PowerStage.h
+++ b/engine/include/amp2203/PowerStage.h
@@ -25,7 +25,7 @@ namespace amp2203 {
 /// resistances as one coupled element, the load); root ports (g, s, p) of each pair against ground.
 class PowerStage {
 public:
-    static constexpr double kSupplyCt = 488.708422, kSupplyScreen = 485.649287;  // CIRCUIT.md §5
+    static constexpr double kSupplyCt = 491.346637, kSupplyScreen = 488.880467;  // CIRCUIT.md §5
     /// J5 Thevenin resistances (harness/junctions.py j5a / j5b, provisional; CIRCUIT.md §4).
     static constexpr double kRthA = 58067.6, kRthB = 56937.4;
     static constexpr int kNodes = 17, kElements = 31, kRootPorts = 6;
diff --git a/engine/include/amp2203/Preamp.h b/engine/include/amp2203/Preamp.h
index f6be57e..e31707a 100644
--- a/engine/include/amp2203/Preamp.h
+++ b/engine/include/amp2203/Preamp.h
@@ -25,14 +25,14 @@ namespace amp2203 {
 /// while one moves, the matrices are recomputed every kParamUpdateInterval samples.
 class Preamp {
 public:
-    static constexpr double kSupplyBpA = 389.349603;  // CIRCUIT.md §5; B7 sets them in M4
-    static constexpr double kSupplyBpX = 402.335999;
+    static constexpr double kSupplyBpA = 391.921506;  // CIRCUIT.md §5 (after D-058); B7 sets them in M4
+    static constexpr double kSupplyBpX = 404.998185;
     static constexpr int kParamUpdateInterval = 128;  // samples between matrix updates while a knob moves (D-057; was 32)
     static constexpr int kNodes = 20, kElements = 38, kRootPorts = 9;  // 8 triode ports + the load at y
 
     // Component values, CIRCUIT.md §1 and tubes.lib (SI units).
     static constexpr double R1 = 2.7e3, R3 = 68e3, R4 = 100e3, R5 = 470e3, R6 = 10e3, R7 = 100e3;
-    static constexpr double C1 = 0.68e-6, C3 = 0.022e-6, C4 = 470e-12, C5 = 1e-9, VR1 = 1e6;
+    static constexpr double C1 = 0.68e-6, C2 = 100e-12, C3 = 0.022e-6, C4 = 470e-12, C5 = 1e-9, VR1 = 1e6;
     static constexpr double R9 = 820.0, R10 = 470e3, R11 = 470e3, R12 = 100e3, R13 = 100e3, R15 = 33e3;
     static constexpr double C7 = 0.022e-6, C8 = 470e-12, C10 = 470e-12, C11 = 0.022e-6, C12 = 0.022e-6;
     static constexpr double VR3 = 220e3, VR4 = 22e3, VR5 = 1e6, VR2 = 1e6;
@@ -114,7 +114,8 @@ class Preamp {
     chowdsp::wdft::ResistorT<double> vr1b_{1.0};
     chowdsp::wdft::ResistorT<double> r6_{R6};
     chowdsp::wdft::ResistiveVoltageSourceT<double> src7_{R7};
-    detail::DcCapacitor cgk1a_{Cgk}, cgp1a_{Cgp}, cpk1a_{Cpk}, cgk1b_{Cgk}, cgp1b_{Cgp}, cpk1b_{Cpk};
+    // cpk1a_: V1a's Cpk in parallel with C2 (100 pF plate–cathode, D-062): one p1a – k1a port
+    detail::DcCapacitor cgk1a_{Cgk}, cgp1a_{Cgp}, cpk1a_{Cpk + C2}, cgk1b_{Cgk}, cgp1b_{Cgp}, cpk1b_{Cpk};
     // B3 elements
     detail::DcCapacitor c7_{C7};
     chowdsp::wdft::ResistorT<double> r10_{R10};
diff --git a/engine/include/amp2203/StageV1aV1b.h b/engine/include/amp2203/StageV1aV1b.h
index 6d13284..dd9af0b 100644
--- a/engine/include/amp2203/StageV1aV1b.h
+++ b/engine/include/amp2203/StageV1aV1b.h
@@ -28,13 +28,13 @@ namespace amp2203 {
 class StageV1aV1b {
 public:
     /// Supply node bpA at the F operating point (CIRCUIT.md §5, as the B12 testbench); B7 sets it in M4.
-    static constexpr double kSupplyBpA = 389.349603;
+    static constexpr double kSupplyBpA = 391.921506;
     static constexpr int kParamUpdateInterval = 32;
     static constexpr int kNodes = 8, kElements = 15, kRootPorts = 4;
 
     // Component values, CIRCUIT.md §1 B12 and tubes.lib (SI units).
     static constexpr double R1 = 2.7e3, R3 = 68e3, R4 = 100e3, R5 = 470e3, R6 = 10e3, R7 = 100e3;
-    static constexpr double C1 = 0.68e-6, C3 = 0.022e-6, C4 = 470e-12, C5 = 1e-9, VR1 = 1e6;
+    static constexpr double C1 = 0.68e-6, C2 = 100e-12, C3 = 0.022e-6, C4 = 470e-12, C5 = 1e-9, VR1 = 1e6;
     static constexpr double Cgk = 2.3e-12, Cgp = 2.4e-12, Cpk = 0.9e-12;
 
     StageV1aV1b();
@@ -90,7 +90,8 @@ class StageV1aV1b {
     chowdsp::wdft::ResistorT<double> vr1b_{1.0};
     chowdsp::wdft::ResistorT<double> r6_{R6};
     chowdsp::wdft::ResistiveVoltageSourceT<double> src7_{R7};
-    detail::DcCapacitor cgk1a_{Cgk}, cgp1a_{Cgp}, cpk1a_{Cpk}, cgk1b_{Cgk}, cgp1b_{Cgp}, cpk1b_{Cpk};
+    // cpk1a_: V1a's Cpk in parallel with C2 (100 pF plate–cathode, D-062): one p1a – k1a port
+    detail::DcCapacitor cgk1a_{Cgk}, cgp1a_{Cgp}, cpk1a_{Cpk + C2}, cgk1b_{Cgk}, cgp1b_{Cgp}, cpk1b_{Cpk};
 
     auto elements() noexcept {
         return std::tie(vin_, k1a_, src4_, c3_, r5c4_, c5vr1a_, vr1b_, r6_, src7_, cgk1a_, cgp1a_, cpk1a_, cgk1b_,
diff --git a/engine/include/amp2203/StageV2aV2b.h b/engine/include/amp2203/StageV2aV2b.h
index 655fcad..4b7373c 100644
--- a/engine/include/amp2203/StageV2aV2b.h
+++ b/engine/include/amp2203/StageV2aV2b.h
@@ -25,7 +25,7 @@ class StageV2aV2b {
     /// J2 Thevenin resistance (harness/junctions.py j2, |Z(1 kHz)| of B12 at p1b; DECISIONS D-018).
     static constexpr double kRth2 = 89732.8;
     /// Supply node bpX at the F operating point (CIRCUIT.md §5, as the B3 testbench); B7 sets it in M4.
-    static constexpr double kSupplyBpX = 402.335999;
+    static constexpr double kSupplyBpX = 404.998185;
     static constexpr int kNodes = 6, kElements = 13, kRootPorts = 4;
 
     // Component values, CIRCUIT.md §1 B3 and tubes.lib (SI units).
diff --git a/engine/include/amp2203/StageV2aV2bToneStack.h b/engine/include/amp2203/StageV2aV2bToneStack.h
index 99f29e1..daca4af 100644
--- a/engine/include/amp2203/StageV2aV2bToneStack.h
+++ b/engine/include/amp2203/StageV2aV2bToneStack.h
@@ -26,7 +26,7 @@ namespace amp2203 {
 class StageV2aV2bToneStack {
 public:
     static constexpr double kRth2 = 89732.8;          // harness/junctions.py j2 (D-018)
-    static constexpr double kSupplyBpX = 402.335999;  // CIRCUIT.md §5; B7 sets it in M4
+    static constexpr double kSupplyBpX = 404.998185;  // CIRCUIT.md §5; B7 sets it in M4
     static constexpr int kParamUpdateInterval = 32;
     static constexpr int kNodes = 13, kElements = 24, kRootPorts = 4;
 
diff --git a/harness/reports/M2/20261018_b12_DEFAULT.md b/harness/reports/M2/20261018_b12_DEFAULT.md
new file mode 100644
index 0000000..42a5169
--- /dev/null
+++ b/harness/reports/M2/20261018_b12_DEFAULT.md
@@ -0,0 +1,198 @@
+# M2 report: b12 / DEFAULT
+
+- Block: B12 StageV1aV1b (V1a + V1b, joint root)
+- Preset: DEFAULT — Default knobs; standard signal set at the block levels
+- Knobs: preampVolume=0.6, treble=0.5, middle=0.5, bass=0.5, master=0.3, presence=0.5
+- Date: 2026-10-18
+- Engine commit: `d37baf0 (dirty)`
+- Testbench: `harness/testbenches/b12.cir` sha256 `ddc48819203d327c`; netlist sha256 `ffd9b2812204248f`; tubes.lib sha256 `c9c9c88346c69010`
+- ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+
+## Summary
+
+PASS 105 · FAIL 0 · INFO 16 (INFO = measured, not scored in M2)
+
+| Check | Item | Measured | Tolerance | Status |
+|---|---|---|---|---|
+| dc_rel_error | v(bpa) | 1.45e-16 | ≤ 0.005 | PASS |
+| dc_rel_error | v(g1a) | 0.0001717 | ≤ 0.005 | PASS |
+| dc_rel_error | v(in) | 0 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k1a) | 4.576e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k1b) | 0.000107 | ≤ 0.005 | PASS |
+| dc_rel_error | v(na) | 0.0006024 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1a) | 1.436e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1b) | 1.121e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(vtop) | 0.0006024 | ≤ 0.005 | PASS |
+| dc_rel_error | v(w1) | 0.0006024 | ≤ 0.005 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.01V | -76.08 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.01V | — | ≤ 0.5 | INFO |
+| thd_pp | SIN-100Hz-0.01V | 1.078e-05 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.01V | 1 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.01V | -68.16 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.01V | 0.0136 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.01V | 0.0001133 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.01V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.01V | -57.18 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.01V | 0.01576 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.01V | 0.0003894 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.01V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.01V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.1V | -76.07 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.1V | 0.0117 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.1V | 0.0001065 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.1V | -68.06 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.1V | 0.02226 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.1V | 0.001254 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.1V | -57.08 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.1V | 0.01389 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.1V | 0.004654 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.5V | -75.63 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.5V | 0.02413 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.5V | 0.0003982 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.5V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.5V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.5V | -64.63 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.5V | 0.163 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.5V | 0.0193 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.5V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.5V | -56.46 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.5V | 0.01751 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.5V | 0.01231 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.5V | 4 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-100Hz-2V | -66.58 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-2V | 0.0261 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-2V | 0.0177 pp | — | INFO |
+| newton_failures | SIN-100Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-2V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-2V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-1000Hz-2V | -67.36 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-2V | 0.01549 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-2V | 0.01299 pp | — | INFO |
+| newton_failures | SIN-1000Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-2V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-2V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-5000Hz-2V | -55.38 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-2V | 0.01022 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-2V | 0.00766 pp | — | INFO |
+| newton_failures | SIN-5000Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-2V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-2V | 6 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-lo-0.01V | -55.39 dB | ≤ -20 | PASS |
+| linear_mag_db_20_10k | SWP-lo-0.01V | 0.01735 dB | ≤ 0.1 | INFO |
+| linear_mag_db_10k_20k | SWP-lo-0.01V | 0.02413 dB | ≤ 0.3 | INFO |
+| method_mag_db_spice_tran_vs_ac | SWP-lo-0.01V | 0.03087 dB | — | INFO |
+| newton_failures | SWP-lo-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-lo-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-lo-0.01V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-hi-0.1V | -55.37 dB | ≤ -20 | PASS |
+| newton_failures | SWP-hi-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-hi-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-hi-0.1V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | TT-0.05V | -73.66 dB | ≤ -20 | PASS |
+| newton_failures | TT-0.05V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | TT-0.05V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | TT-0.05V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | BURST-0.5V | -64.63 dB | ≤ -20 | PASS |
+| newton_failures | BURST-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | BURST-0.5V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | BURST-0.5V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | STEP-0.1V | -61.4 dB | ≤ -20 | PASS |
+| newton_failures | STEP-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | STEP-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | STEP-0.1V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR L | -69.48 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR L | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR L | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR L | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR LL | -69.44 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR LL | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR LL | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR LL | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR R | -69.73 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR R | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR R | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR R | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR RR | -69.16 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR RR | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR RR | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR RR | 3 | ≤ 12 | PASS |
+
+## Signals
+
+| Signal | Peak F [V] | ESR [dB] | Best lag | ESR at lag [dB] | THD F / E [%] | Power F / E [W] | ns/sample | Newton fail / median / max it |
+|---|---|---|---|---|---|---|---|---|
+| SIN-100Hz-0.01V | 0.2762 | -76.08 | 0 | -76.08 | 0.00925 / 0.00926 | — | 289.6 | 0 / 1 / 1 |
+| SIN-1000Hz-0.01V | 1.275 | -68.16 | 0 | -68.16 | 0.0634 / 0.0632 | — | 292.0 | 0 / 1 / 2 |
+| SIN-5000Hz-0.01V | 2.832 | -57.18 | 0 | -57.18 | 0.151 / 0.15 | — | 458.8 | 0 / 2 / 2 |
+| SIN-100Hz-0.1V | 2.763 | -76.07 | 0 | -76.07 | 0.0902 / 0.0904 | — | 286.9 | 0 / 1 / 2 |
+| SIN-1000Hz-0.1V | 12.83 | -68.06 | 0 | -68.06 | 0.655 / 0.653 | — | 404.5 | 0 / 2 / 2 |
+| SIN-5000Hz-0.1V | 28.88 | -57.08 | 0 | -57.08 | 1.98 / 1.98 | — | 438.8 | 0 / 2 / 2 |
+| SIN-100Hz-0.5V | 13.79 | -75.63 | 0 | -75.63 | 0.462 / 0.463 | — | 290.5 | 0 / 1 / 2 |
+| SIN-1000Hz-0.5V | 63.77 | -64.63 | 0 | -64.63 | 12.8 / 12.8 | — | 433.1 | 0 / 2 / 2 |
+| SIN-5000Hz-0.5V | 146 | -56.46 | 0 | -56.46 | 27.4 / 27.4 | — | 477.0 | 0 / 2 / 4 |
+| SIN-100Hz-2V | 52.13 | -66.58 | 0 | -66.58 | 8.21 / 8.2 | — | 288.3 | 0 / 1 / 2 |
+| SIN-1000Hz-2V | 226.3 | -67.36 | 0 | -67.36 | 30.2 / 30.2 | — | 465.7 | 0 / 2 / 3 |
+| SIN-5000Hz-2V | 270 | -55.38 | 0 | -55.38 | 34.3 / 34.3 | — | 509.1 | 0 / 2 / 6 |
+| SWP-lo-0.01V | 2.746 | -55.39 | 0 | -55.39 | — | — | 334.1 | 0 / 1 / 3 |
+| SWP-hi-0.1V | 28.05 | -55.37 | 0 | -55.37 | — | — | 361.8 | 0 / 1 / 3 |
+| TT-0.05V | 5.308 | -73.66 | 0 | -73.66 | — | — | 286.1 | 0 / 1 / 2 |
+| BURST-0.5V | 63.74 | -64.63 | 0 | -64.63 | — | — | 359.5 | 0 / 1 / 3 |
+| STEP-0.1V | 22.79 | -61.40 | 0 | -61.40 | — | — | 299.0 | 0 / 1 / 3 |
+| DI-GTR L | 126 | -69.48 | 0 | -69.48 | — | — | 312.4 | 0 / 1 / 2 |
+| DI-GTR LL | 122.9 | -69.44 | 0 | -69.44 | — | — | 307.1 | 0 / 1 / 3 |
+| DI-GTR R | 114.5 | -69.73 | 0 | -69.73 | — | — | 306.4 | 0 / 1 / 3 |
+| DI-GTR RR | 121.1 | -69.16 | 0 | -69.16 | — | — | 308.5 | 0 / 1 / 3 |
+
+## DC operating point
+
+| Node | SPICE [V] | Engine [V] | Rel. error |
+|---|---|---|---|
+| bpa | 391.9215 | 391.9215 | 1.45e-16 |
+| g1a | 0.0001 | 0.0001 | 0.0001717 |
+| in | 0.0000 | 0.0000 | 0 |
+| k1a | 2.5271 | 2.5270 | 4.576e-05 |
+| k1b | 3.7171 | 3.7167 | 0.000107 |
+| na | 0.0002 | 0.0002 | 0.0006024 |
+| p1a | 298.3260 | 298.3303 | 1.436e-05 |
+| p1b | 354.7502 | 354.7542 | 1.121e-05 |
+| vtop | 0.0002 | 0.0002 | 0.0006024 |
+| w1 | 0.0002 | 0.0002 | 0.0006024 |
+
+Engine values are the probe values after the first sample (zero input) following `reset()`. Nodes the engine does not probe yet show —.
+
+## Figures
+
+### Waveform overlay and error (most demanding signal)
+
+![Waveform overlay and error (most demanding signal)](20261018_b12_DEFAULT/waveform.png)
+
+### Harmonics
+
+![Harmonics](20261018_b12_DEFAULT/harmonics.png)
+
+### Magnitude response
+
+![Magnitude response](20261018_b12_DEFAULT/magnitude.png)
+
+### Spectrogram (DI)
+
+![Spectrogram (DI)](20261018_b12_DEFAULT/spectrogram.png)
diff --git a/harness/reports/M2/20261018_b12_DEFAULT/harmonics.png b/harness/reports/M2/20261018_b12_DEFAULT/harmonics.png
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diff --git a/harness/reports/M2/20261018_b12_DEFAULT/spectrogram.png b/harness/reports/M2/20261018_b12_DEFAULT/spectrogram.png
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diff --git a/harness/reports/M2/20261018_b12_DEFAULT/waveform.png b/harness/reports/M2/20261018_b12_DEFAULT/waveform.png
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diff --git a/harness/reports/M2/20261018_b12_VOL0.2.md b/harness/reports/M2/20261018_b12_VOL0.2.md
new file mode 100644
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--- /dev/null
+++ b/harness/reports/M2/20261018_b12_VOL0.2.md
@@ -0,0 +1,198 @@
+# M2 report: b12 / VOL0.2
+
+- Block: B12 StageV1aV1b (V1a + V1b, joint root)
+- Preset: VOL0.2 — Preamp Volume 0.2; standard signal set (M2)
+- Knobs: preampVolume=0.2, treble=0.5, middle=0.5, bass=0.5, master=0.3, presence=0.5
+- Date: 2026-10-18
+- Engine commit: `d37baf0 (dirty)`
+- Testbench: `harness/testbenches/b12.cir` sha256 `ddc48819203d327c`; netlist sha256 `ffd9b2812204248f`; tubes.lib sha256 `c9c9c88346c69010`
+- ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+
+## Summary
+
+PASS 106 · FAIL 0 · INFO 15 (INFO = measured, not scored in M2)
+
+| Check | Item | Measured | Tolerance | Status |
+|---|---|---|---|---|
+| dc_rel_error | v(bpa) | 1.45e-16 | ≤ 0.005 | PASS |
+| dc_rel_error | v(g1a) | 0.0001717 | ≤ 0.005 | PASS |
+| dc_rel_error | v(in) | 0 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k1a) | 4.576e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k1b) | 0.0001069 | ≤ 0.005 | PASS |
+| dc_rel_error | v(na) | 6.543e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1a) | 1.436e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1b) | 1.12e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(vtop) | 6.543e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(w1) | 6.543e-05 | ≤ 0.005 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.01V | -76.23 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.01V | 0.001939 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.01V | 9.992e-06 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.01V | 1 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.01V | -69.84 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.01V | 0.0001541 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.01V | 2.054e-05 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.01V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.01V | -58.53 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.01V | 0.01449 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.01V | 8.281e-05 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.01V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.01V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.1V | -76.23 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.1V | 0.001969 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.1V | 0.0001001 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.1V | -69.83 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.1V | 0.005029 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.1V | 0.0002044 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.1V | -58.53 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.1V | 0.08524 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.1V | 0.0008574 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.5V | -76.19 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.5V | 0.005208 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.5V | 0.0005098 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.5V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.5V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.5V | -69.67 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.5V | 0.0147 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.5V | 0.001054 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.5V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.5V | -58.39 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.5V | 0.01418 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.5V | 0.003571 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.5V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-100Hz-2V | -75.41 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-2V | 0.008804 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-2V | 0.002683 pp | — | INFO |
+| newton_failures | SIN-100Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-2V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-2V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-1000Hz-2V | -66.81 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-2V | 0.01702 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-2V | 0.006508 pp | — | INFO |
+| newton_failures | SIN-1000Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-2V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-2V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-5000Hz-2V | -57.12 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-2V | 0.02244 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-2V | 0.001298 pp | — | INFO |
+| newton_failures | SIN-5000Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-2V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-2V | 4 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-lo-0.01V | -53.06 dB | ≤ -20 | PASS |
+| linear_mag_db_20_10k | SWP-lo-0.01V | 0.02046 dB | ≤ 0.1 | INFO |
+| linear_mag_db_10k_20k | SWP-lo-0.01V | 0.0127 dB | ≤ 0.3 | INFO |
+| method_mag_db_spice_tran_vs_ac | SWP-lo-0.01V | 0.02721 dB | — | INFO |
+| newton_failures | SWP-lo-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-lo-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-lo-0.01V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-hi-0.1V | -53.06 dB | ≤ -20 | PASS |
+| newton_failures | SWP-hi-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-hi-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-hi-0.1V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | TT-0.05V | -74.31 dB | ≤ -20 | PASS |
+| newton_failures | TT-0.05V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | TT-0.05V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | TT-0.05V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | BURST-0.5V | -69.68 dB | ≤ -20 | PASS |
+| newton_failures | BURST-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | BURST-0.5V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | BURST-0.5V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | STEP-0.1V | -56.71 dB | ≤ -20 | PASS |
+| newton_failures | STEP-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | STEP-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | STEP-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR L | -71.2 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR L | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR L | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR L | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR LL | -70.92 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR LL | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR LL | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR LL | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR R | -71.3 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR R | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR R | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR R | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR RR | -71.15 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR RR | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR RR | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR RR | 2 | ≤ 12 | PASS |
+
+## Signals
+
+| Signal | Peak F [V] | ESR [dB] | Best lag | ESR at lag [dB] | THD F / E [%] | Power F / E [W] | ns/sample | Newton fail / median / max it |
+|---|---|---|---|---|---|---|---|---|
+| SIN-100Hz-0.01V | 0.03095 | -76.23 | 0 | -76.23 | 0.0269 / 0.0269 | — | 285.1 | 0 / 1 / 1 |
+| SIN-1000Hz-0.01V | 0.1658 | -69.84 | 0 | -69.84 | 0.0938 / 0.0938 | — | 290.9 | 0 / 1 / 2 |
+| SIN-5000Hz-0.01V | 0.5588 | -58.53 | 0 | -58.53 | 0.0802 / 0.0803 | — | 400.1 | 0 / 2 / 2 |
+| SIN-100Hz-0.1V | 0.3086 | -76.23 | 0 | -76.23 | 0.267 / 0.267 | — | 288.2 | 0 / 1 / 2 |
+| SIN-1000Hz-0.1V | 1.647 | -69.83 | 0 | -69.83 | 0.939 / 0.939 | — | 289.6 | 0 / 1 / 2 |
+| SIN-5000Hz-0.1V | 5.585 | -58.53 | 0 | -58.53 | 0.802 / 0.803 | — | 433.9 | 0 / 2 / 2 |
+| SIN-100Hz-0.5V | 1.529 | -76.19 | 0 | -76.19 | 1.34 / 1.34 | — | 287.7 | 0 / 1 / 2 |
+| SIN-1000Hz-0.5V | 8.292 | -69.67 | 0 | -69.67 | 4.76 / 4.76 | — | 381.1 | 0 / 2 / 2 |
+| SIN-5000Hz-0.5V | 27.55 | -58.39 | 0 | -58.39 | 4.03 / 4.03 | — | 437.6 | 0 / 2 / 3 |
+| SIN-100Hz-2V | 6.256 | -75.41 | 0 | -75.41 | 5.98 / 5.98 | — | 286.8 | 0 / 1 / 2 |
+| SIN-1000Hz-2V | 31.68 | -66.81 | 0 | -66.81 | 22.9 / 22.9 | — | 430.5 | 0 / 2 / 3 |
+| SIN-5000Hz-2V | 101.4 | -57.12 | 0 | -57.12 | 26.7 / 26.7 | — | 476.8 | 0 / 2 / 4 |
+| SWP-lo-0.01V | 0.7803 | -53.06 | 0 | -53.06 | — | — | 319.2 | 0 / 1 / 3 |
+| SWP-hi-0.1V | 7.821 | -53.06 | 0 | -53.06 | — | — | 337.8 | 0 / 1 / 3 |
+| TT-0.05V | 0.6466 | -74.31 | 0 | -74.31 | — | — | 288.3 | 0 / 1 / 2 |
+| BURST-0.5V | 8.292 | -69.68 | 0 | -69.68 | — | — | 331.2 | 0 / 1 / 2 |
+| STEP-0.1V | 5.434 | -56.71 | 0 | -56.71 | — | — | 292.5 | 0 / 1 / 2 |
+| DI-GTR L | 15.65 | -71.20 | 0 | -71.20 | — | — | 288.8 | 0 / 1 / 2 |
+| DI-GTR LL | 15.26 | -70.92 | 0 | -70.92 | — | — | 281.9 | 0 / 1 / 2 |
+| DI-GTR R | 13.84 | -71.30 | 0 | -71.30 | — | — | 287.1 | 0 / 1 / 2 |
+| DI-GTR RR | 15.42 | -71.15 | 0 | -71.15 | — | — | 285.3 | 0 / 1 / 2 |
+
+## DC operating point
+
+| Node | SPICE [V] | Engine [V] | Rel. error |
+|---|---|---|---|
+| bpa | 391.9215 | 391.9215 | 1.45e-16 |
+| g1a | 0.0001 | 0.0001 | 0.0001717 |
+| in | 0.0000 | 0.0000 | 0 |
+| k1a | 2.5271 | 2.5270 | 4.576e-05 |
+| k1b | 3.7170 | 3.7166 | 0.0001069 |
+| na | 0.0000 | 0.0000 | 6.543e-05 |
+| p1a | 298.3260 | 298.3303 | 1.436e-05 |
+| p1b | 354.7514 | 354.7553 | 1.12e-05 |
+| vtop | 0.0000 | 0.0000 | 6.543e-05 |
+| w1 | 0.0000 | 0.0000 | 6.543e-05 |
+
+Engine values are the probe values after the first sample (zero input) following `reset()`. Nodes the engine does not probe yet show —.
+
+## Figures
+
+### Waveform overlay and error (most demanding signal)
+
+![Waveform overlay and error (most demanding signal)](20261018_b12_VOL0.2/waveform.png)
+
+### Harmonics
+
+![Harmonics](20261018_b12_VOL0.2/harmonics.png)
+
+### Magnitude response
+
+![Magnitude response](20261018_b12_VOL0.2/magnitude.png)
+
+### Spectrogram (DI)
+
+![Spectrogram (DI)](20261018_b12_VOL0.2/spectrogram.png)
diff --git a/harness/reports/M2/20261018_b12_VOL0.2/harmonics.png b/harness/reports/M2/20261018_b12_VOL0.2/harmonics.png
new file mode 100644
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diff --git a/harness/reports/M2/20261018_b12_VOL1.0.md b/harness/reports/M2/20261018_b12_VOL1.0.md
new file mode 100644
index 0000000..22b25e4
--- /dev/null
+++ b/harness/reports/M2/20261018_b12_VOL1.0.md
@@ -0,0 +1,198 @@
+# M2 report: b12 / VOL1.0
+
+- Block: B12 StageV1aV1b (V1a + V1b, joint root)
+- Preset: VOL1.0 — Preamp Volume 1.0; standard signal set (M2)
+- Knobs: preampVolume=1, treble=0.5, middle=0.5, bass=0.5, master=0.3, presence=0.5
+- Date: 2026-10-18
+- Engine commit: `d37baf0 (dirty)`
+- Testbench: `harness/testbenches/b12.cir` sha256 `ddc48819203d327c`; netlist sha256 `ffd9b2812204248f`; tubes.lib sha256 `c9c9c88346c69010`
+- ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+
+## Summary
+
+PASS 106 · FAIL 0 · INFO 15 (INFO = measured, not scored in M2)
+
+| Check | Item | Measured | Tolerance | Status |
+|---|---|---|---|---|
+| dc_rel_error | v(bpa) | 1.45e-16 | ≤ 0.005 | PASS |
+| dc_rel_error | v(g1a) | 0.0001717 | ≤ 0.005 | PASS |
+| dc_rel_error | v(in) | 0 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k1a) | 4.576e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k1b) | 0.0001076 | ≤ 0.005 | PASS |
+| dc_rel_error | v(na) | 0.003703 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1a) | 1.436e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1b) | 1.128e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(vtop) | 0.003703 | ≤ 0.005 | PASS |
+| dc_rel_error | v(w1) | 0.003703 | ≤ 0.005 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.01V | -75.65 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.01V | 0.01302 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.01V | 0.0001619 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.01V | 1 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.01V | -66.56 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.01V | 0.01679 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.01V | 0.0004362 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.01V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.01V | -57.21 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.01V | 0.01187 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.01V | 0.0004926 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.01V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.01V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.1V | -75.15 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.1V | 0.0242 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.1V | 0.001852 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.1V | -65.65 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.1V | 0.02272 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.1V | 0.007833 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.1V | -57.01 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.1V | 0.00886 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.1V | 0.006626 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.5V | -67.4 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.5V | 0.04441 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.5V | 0.0174 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.5V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.5V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.5V | -65.17 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.5V | 0.01001 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.5V | 0.01103 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.5V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.5V | -56.6 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.5V | 0.0126 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.5V | 0.01142 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.5V | 4 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-100Hz-2V | -74.08 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-2V | 0.0105 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-2V | 0.003024 pp | — | INFO |
+| newton_failures | SIN-100Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-2V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-2V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-1000Hz-2V | -64.32 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-2V | 0.001354 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-2V | 0.0006628 pp | — | INFO |
+| newton_failures | SIN-1000Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-2V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-2V | 4 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-5000Hz-2V | -54.32 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-2V | 0.01782 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-2V | 0.009844 pp | — | INFO |
+| newton_failures | SIN-5000Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-2V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-2V | 7 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-lo-0.01V | -58.57 dB | ≤ -20 | PASS |
+| linear_mag_db_20_10k | SWP-lo-0.01V | 0.02988 dB | ≤ 0.1 | INFO |
+| linear_mag_db_10k_20k | SWP-lo-0.01V | 0.0343 dB | ≤ 0.3 | INFO |
+| method_mag_db_spice_tran_vs_ac | SWP-lo-0.01V | 0.03277 dB | — | INFO |
+| newton_failures | SWP-lo-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-lo-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-lo-0.01V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-hi-0.1V | -58.41 dB | ≤ -20 | PASS |
+| newton_failures | SWP-hi-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-hi-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-hi-0.1V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | TT-0.05V | -71.86 dB | ≤ -20 | PASS |
+| newton_failures | TT-0.05V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | TT-0.05V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | TT-0.05V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | BURST-0.5V | -65.18 dB | ≤ -20 | PASS |
+| newton_failures | BURST-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | BURST-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | BURST-0.5V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | STEP-0.1V | -68.47 dB | ≤ -20 | PASS |
+| newton_failures | STEP-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | STEP-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | STEP-0.1V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR L | -68.01 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR L | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR L | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR L | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR LL | -68.29 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR LL | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR LL | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR LL | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR R | -68.31 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR R | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR R | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR R | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | DI-GTR RR | -67.83 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR RR | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR RR | 1 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR RR | 4 | ≤ 12 | PASS |
+
+## Signals
+
+| Signal | Peak F [V] | ESR [dB] | Best lag | ESR at lag [dB] | THD F / E [%] | Power F / E [W] | ns/sample | Newton fail / median / max it |
+|---|---|---|---|---|---|---|---|---|
+| SIN-100Hz-0.01V | 1.598 | -75.65 | 0 | -75.65 | 0.0981 / 0.0979 | — | 291.0 | 0 / 1 / 1 |
+| SIN-1000Hz-0.01V | 3.577 | -66.56 | 0 | -66.56 | 0.195 / 0.195 | — | 292.6 | 0 / 1 / 2 |
+| SIN-5000Hz-0.01V | 3.859 | -57.21 | 0 | -57.21 | 0.225 / 0.225 | — | 438.5 | 0 / 2 / 2 |
+| SIN-100Hz-0.1V | 16.22 | -75.15 | 0 | -75.15 | 1.06 / 1.06 | — | 293.0 | 0 / 1 / 2 |
+| SIN-1000Hz-0.1V | 36.57 | -65.65 | 0 | -65.65 | 3.14 / 3.13 | — | 430.3 | 0 / 2 / 2 |
+| SIN-5000Hz-0.1V | 39.52 | -57.01 | 0 | -57.01 | 3.78 / 3.78 | — | 440.0 | 0 / 2 / 2 |
+| SIN-100Hz-0.5V | 83.21 | -67.40 | 0 | -67.40 | 19.4 / 19.4 | — | 294.2 | 0 / 1 / 2 |
+| SIN-1000Hz-0.5V | 183.1 | -65.17 | 0 | -65.17 | 30.2 / 30.1 | — | 404.0 | 0 / 2 / 3 |
+| SIN-5000Hz-0.5V | 199.1 | -56.60 | 0 | -56.60 | 31.2 / 31.2 | — | 493.5 | 0 / 2 / 4 |
+| SIN-100Hz-2V | 230.6 | -74.08 | 0 | -74.08 | 35 / 35 | — | 329.2 | 0 / 1 / 2 |
+| SIN-1000Hz-2V | 250.7 | -64.32 | 0 | -64.32 | 40 / 40 | — | 467.1 | 0 / 2 / 4 |
+| SIN-5000Hz-2V | 274.5 | -54.32 | 0 | -54.32 | 49 / 49 | — | 504.2 | 0 / 2 / 7 |
+| SWP-lo-0.01V | 3.826 | -58.57 | 0 | -58.57 | — | — | 344.4 | 0 / 1 / 3 |
+| SWP-hi-0.1V | 39.33 | -58.41 | 0 | -58.41 | — | — | 377.6 | 0 / 2 / 3 |
+| TT-0.05V | 22.4 | -71.86 | 0 | -71.86 | — | — | 288.0 | 0 / 1 / 2 |
+| BURST-0.5V | 182.9 | -65.18 | 0 | -65.18 | — | — | 365.7 | 0 / 2 / 3 |
+| STEP-0.1V | 37.88 | -68.47 | 0 | -68.47 | — | — | 297.0 | 0 / 1 / 3 |
+| DI-GTR L | 237.4 | -68.01 | 0 | -68.01 | — | — | 314.2 | 0 / 1 / 3 |
+| DI-GTR LL | 236.9 | -68.29 | 0 | -68.29 | — | — | 306.5 | 0 / 1 / 3 |
+| DI-GTR R | 238.4 | -68.31 | 0 | -68.31 | — | — | 310.8 | 0 / 1 / 3 |
+| DI-GTR RR | 238.1 | -67.83 | 0 | -67.83 | — | — | 312.9 | 0 / 1 / 4 |
+
+## DC operating point
+
+| Node | SPICE [V] | Engine [V] | Rel. error |
+|---|---|---|---|
+| bpa | 391.9215 | 391.9215 | 1.45e-16 |
+| g1a | 0.0001 | 0.0001 | 0.0001717 |
+| in | 0.0000 | 0.0000 | 0 |
+| k1a | 2.5271 | 2.5270 | 4.576e-05 |
+| k1b | 3.7178 | 3.7174 | 0.0001076 |
+| na | 0.0010 | 0.0010 | 0.003703 |
+| p1a | 298.3260 | 298.3303 | 1.436e-05 |
+| p1b | 354.7437 | 354.7477 | 1.128e-05 |
+| vtop | 0.0010 | 0.0010 | 0.003703 |
+| w1 | 0.0010 | 0.0010 | 0.003703 |
+
+Engine values are the probe values after the first sample (zero input) following `reset()`. Nodes the engine does not probe yet show —.
+
+## Figures
+
+### Waveform overlay and error (most demanding signal)
+
+![Waveform overlay and error (most demanding signal)](20261018_b12_VOL1.0/waveform.png)
+
+### Harmonics
+
+![Harmonics](20261018_b12_VOL1.0/harmonics.png)
+
+### Magnitude response
+
+![Magnitude response](20261018_b12_VOL1.0/magnitude.png)
+
+### Spectrogram (DI)
+
+![Spectrogram (DI)](20261018_b12_VOL1.0/spectrogram.png)
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diff --git a/harness/reports/M2/20261018_b12_knob_jump.md b/harness/reports/M2/20261018_b12_knob_jump.md
new file mode 100644
index 0000000..1317893
--- /dev/null
+++ b/harness/reports/M2/20261018_b12_knob_jump.md
@@ -0,0 +1,9 @@
+# M2 report: B12 knob-jump test
+
+- Date: 2026-10-18, engine commit `d37baf0 (dirty)`, ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+- Knob targets 0 → 1 in 10 ms from t = 20 ms during a 1000 Hz, 0.1 V tone at the guitar input (DC 0.0000 V); other knobs at their defaults. Engine: smoothing 20 ms, matrix update every 32 samples. SPICE: pot resistances follow the same smoothed trajectory continuously.
+- Window: the ramp and the 20 ms after it. Pass (D-025): no NaN/Inf, ESR ≤ -20 dB.
+
+| Case | Finite | ESR | Status | Peak error / ref peak | Error energy > 5 kHz vs tone |
+|---|---|---|---|---|---|
+| preampVolume | yes | -55.9 dB | PASS | 1.31e-03 | -64.9 dB |
diff --git a/harness/reports/M3/20261018_b1234_DEFAULT.md b/harness/reports/M3/20261018_b1234_DEFAULT.md
new file mode 100644
index 0000000..f8d0223
--- /dev/null
+++ b/harness/reports/M3/20261018_b1234_DEFAULT.md
@@ -0,0 +1,224 @@
+# M3 report: b1234 / DEFAULT
+
+- Block: B1234 Preamp (B12 + B3 + B4 in one tree, 8-port root, D-038)
+- Preset: DEFAULT — Default knobs; standard signal set at the block levels
+- Knobs: preampVolume=0.6, treble=0.5, middle=0.5, bass=0.5, master=0.3, presence=0.5
+- Date: 2026-10-18
+- Engine commit: `d37baf0 (dirty)`
+- Testbench: `harness/testbenches/b1234.cir` sha256 `a99cb5b98a48184b`; netlist sha256 `ffd9b2812204248f`; tubes.lib sha256 `c9c9c88346c69010`
+- ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+
+## Summary
+
+PASS 119 · FAIL 0 · INFO 15 (INFO = measured, not scored in M3)
+
+| Check | Item | Measured | Tolerance | Status |
+|---|---|---|---|---|
+| dc_rel_error | v(bpa) | 1.45e-16 | ≤ 0.005 | PASS |
+| dc_rel_error | v(bpx) | 0 | ≤ 0.005 | PASS |
+| dc_rel_error | v(g1a) | 0.0001717 | ≤ 0.005 | PASS |
+| dc_rel_error | v(g2a) | 0.0006604 | ≤ 0.005 | PASS |
+| dc_rel_error | v(in) | 0 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k1a) | 4.576e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k1b) | 0.000107 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k2a) | 2.495e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k2b) | 1.794e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(mw) | 1.175e-08 | ≤ 0.005 | PASS |
+| dc_rel_error | v(na) | 0.0006024 | ≤ 0.005 | PASS |
+| dc_rel_error | v(nb) | 0.0006604 | ≤ 0.005 | PASS |
+| dc_rel_error | v(nbb) | 1.175e-08 | ≤ 0.005 | PASS |
+| dc_rel_error | v(nd) | 1.794e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(ne) | 1.179e-08 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1a) | 1.436e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1b) | 1.121e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p2a) | 1.85e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(tt) | 8.356e-09 | ≤ 0.005 | PASS |
+| dc_rel_error | v(tw) | 9.614e-09 | ≤ 0.005 | PASS |
+| dc_rel_error | v(vtop) | 0.0006024 | ≤ 0.005 | PASS |
+| dc_rel_error | v(w1) | 0.0006024 | ≤ 0.005 | PASS |
+| dc_rel_error | v(y) | 3.257e-10 | ≤ 0.005 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.01V | -73.08 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.01V | 0.002595 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.01V | 1.433e-05 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.01V | 2 | ≤ 32 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.01V | -60.63 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.01V | 0.01803 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.01V | 0.001323 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.01V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.01V | 2 | ≤ 32 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.01V | -53.07 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.01V | 0.1088 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.01V | 0.03125 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.01V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.01V | 6 | ≤ 32 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.1V | -73.53 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.1V | 0.02799 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.1V | 0.001435 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.1V | 2 | ≤ 32 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.1V | -57.75 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.1V | 0.02889 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.1V | 0.007326 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.1V | 6 | ≤ 32 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.1V | -47.24 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.1V | 0.03821 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.1V | 0.008787 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.1V | 3 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.1V | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.5V | -75.29 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.5V | 0.002416 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.5V | 6.976e-05 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.5V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.5V | 5 | ≤ 32 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.5V | -50.57 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.5V | 0.02096 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.5V | 0.005945 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.5V | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.5V | -39.33 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.5V | 0.0322 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.5V | 0.00618 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.5V | 3 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.5V | 9 | ≤ 32 | PASS |
+| nonlinear_esr_db_overdrive | SIN-100Hz-2V | -70.14 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-2V | 0.00951 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-2V | 0.004205 pp | — | INFO |
+| newton_failures | SIN-100Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-2V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-2V | 5 | ≤ 32 | PASS |
+| nonlinear_esr_db_overdrive | SIN-1000Hz-2V | -47.39 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-2V | 0.00316 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-2V | 0.0003278 pp | — | INFO |
+| newton_failures | SIN-1000Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-2V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-2V | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db_overdrive | SIN-5000Hz-2V | -34.32 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-2V | 0.1697 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-2V | 0.007558 pp | — | INFO |
+| newton_failures | SIN-5000Hz-2V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-2V | 3 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-2V | 10 | ≤ 32 | PASS |
+| nonlinear_esr_db | SWP-lo-0.01V | -51.28 dB | ≤ -20 | PASS |
+| linear_mag_db_20_10k | SWP-lo-0.01V | 1.146 dB | ≤ 0.1 | INFO |
+| linear_mag_db_10k_20k | SWP-lo-0.01V | 1.073 dB | ≤ 0.3 | INFO |
+| method_mag_db_spice_tran_vs_ac | SWP-lo-0.01V | 1.155 dB | — | INFO |
+| newton_failures | SWP-lo-0.01V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-lo-0.01V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-lo-0.01V | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db | SWP-hi-0.1V | -46.6 dB | ≤ -20 | PASS |
+| newton_failures | SWP-hi-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-hi-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-hi-0.1V | 10 | ≤ 32 | PASS |
+| nonlinear_esr_db | TT-0.05V | -69.19 dB | ≤ -20 | PASS |
+| newton_failures | TT-0.05V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | TT-0.05V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | TT-0.05V | 3 | ≤ 32 | PASS |
+| nonlinear_esr_db | BURST-0.5V | -51.14 dB | ≤ -20 | PASS |
+| newton_failures | BURST-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | BURST-0.5V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | BURST-0.5V | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db | STEP-0.1V | -56.98 dB | ≤ -20 | PASS |
+| newton_failures | STEP-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | STEP-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | STEP-0.1V | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db | DI-GTR L | -62.5 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR L | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR L | 2 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR L | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db | DI-GTR LL | -62.95 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR LL | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR LL | 2 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR LL | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db | DI-GTR R | -63.68 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR R | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR R | 2 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR R | 7 | ≤ 32 | PASS |
+| nonlinear_esr_db | DI-GTR RR | -62.6 dB | ≤ -20 | PASS |
+| newton_failures | DI-GTR RR | 0 | ≤ 0 | PASS |
+| newton_median_iterations | DI-GTR RR | 2 | ≤ 3 | PASS |
+| newton_max_iterations | DI-GTR RR | 7 | ≤ 32 | PASS |
+
+## Signals
+
+| Signal | Peak F [V] | ESR [dB] | Best lag | ESR at lag [dB] | THD F / E [%] | Power F / E [W] | ns/sample | Newton fail / median / max it |
+|---|---|---|---|---|---|---|---|---|
+| SIN-100Hz-0.01V | 0.1088 | -73.08 | 0 | -73.08 | 0.129 / 0.129 | — | 729.9 | 0 / 1 / 2 |
+| SIN-1000Hz-0.01V | 0.4171 | -60.63 | 0 | -60.63 | 0.864 / 0.866 | — | 1085.8 | 0 / 2 / 2 |
+| SIN-5000Hz-0.01V | 1.39 | -53.07 | 0 | -53.07 | 6.4 / 6.43 | — | 1238.8 | 0 / 2 / 6 |
+| SIN-100Hz-0.1V | 1.071 | -73.53 | 0 | -73.53 | 1.65 / 1.65 | — | 741.1 | 0 / 1 / 2 |
+| SIN-1000Hz-0.1V | 1.771 | -57.75 | 0 | -57.75 | 42.6 / 42.6 | — | 1142.8 | 0 / 2 / 6 |
+| SIN-5000Hz-0.1V | 2.482 | -47.24 | 0 | -47.24 | 48 / 48 | — | 1437.1 | 0 / 3 / 7 |
+| SIN-100Hz-0.5V | 2.723 | -75.29 | 0 | -75.29 | 15.9 / 15.9 | — | 777.2 | 0 / 1 / 5 |
+| SIN-1000Hz-0.5V | 2.543 | -50.57 | 0 | -50.57 | 63.6 / 63.6 | — | 1116.4 | 0 / 2 / 7 |
+| SIN-5000Hz-0.5V | 2.549 | -39.33 | 0 | -39.33 | 44.7 / 44.7 | — | 1451.0 | 0 / 3 / 9 |
+| SIN-100Hz-2V | 2.881 | -70.14 | 0 | -70.14 | 28.2 / 28.3 | — | 779.8 | 0 / 1 / 5 |
+| SIN-1000Hz-2V | 2.798 | -47.39 | 0 | -47.39 | 63.6 / 63.6 | — | 1228.5 | 0 / 2 / 7 |
+| SIN-5000Hz-2V | 2.542 | -34.32 | 0 | -34.32 | 44.4 / 44.5 | — | 1438.5 | 0 / 3 / 10 |
+| SWP-lo-0.01V | 1.367 | -51.28 | 0 | -51.28 | — | — | 957.7 | 0 / 1 / 7 |
+| SWP-hi-0.1V | 1.928 | -46.60 | 0 | -46.60 | — | — | 1099.4 | 0 / 2 / 10 |
+| TT-0.05V | 1.627 | -69.19 | 0 | -69.19 | — | — | 805.5 | 0 / 1 / 3 |
+| BURST-0.5V | 2.548 | -51.14 | 0 | -51.14 | — | — | 1138.4 | 0 / 2 / 7 |
+| STEP-0.1V | 2.403 | -56.98 | 0 | -56.98 | — | — | 882.0 | 0 / 1 / 7 |
+| DI-GTR L | 2.564 | -62.50 | 0 | -62.50 | — | — | 954.6 | 0 / 2 / 7 |
+| DI-GTR LL | 2.571 | -62.95 | 0 | -62.95 | — | — | 952.9 | 0 / 2 / 7 |
+| DI-GTR R | 2.628 | -63.68 | 0 | -63.68 | — | — | 950.9 | 0 / 2 / 7 |
+| DI-GTR RR | 2.679 | -62.60 | 0 | -62.60 | — | — | 966.2 | 0 / 2 / 7 |
+
+## DC operating point
+
+| Node | SPICE [V] | Engine [V] | Rel. error |
+|---|---|---|---|
+| bpa | 391.9215 | 391.9215 | 1.45e-16 |
+| bpx | 404.9982 | 404.9982 | 0 |
+| g1a | 0.0001 | 0.0001 | 0.0001717 |
+| g2a | 0.0005 | 0.0005 | 0.0006604 |
+| in | 0.0000 | 0.0000 | 0 |
+| k1a | 2.5271 | 2.5270 | 4.576e-05 |
+| k1b | 3.7171 | 3.7167 | 0.000107 |
+| k2a | 1.4139 | 1.4138 | 2.495e-05 |
+| k2b | 233.1404 | 233.1446 | 1.794e-05 |
+| mw | 0.0000 | -0.0000 | 1.175e-08 |
+| na | 0.0002 | 0.0002 | 0.0006024 |
+| nb | 0.0005 | 0.0005 | 0.0006604 |
+| nbb | 0.0000 | -0.0000 | 1.175e-08 |
+| nd | 233.1404 | 233.1446 | 1.794e-05 |
+| ne | 0.0000 | -0.0000 | 1.179e-08 |
+| p1a | 298.3260 | 298.3303 | 1.436e-05 |
+| p1b | 354.7502 | 354.7542 | 1.121e-05 |
+| p2a | 232.5771 | 232.5814 | 1.85e-05 |
+| tt | 0.0000 | -0.0000 | 8.356e-09 |
+| tw | 0.0000 | -0.0000 | 9.614e-09 |
+| vtop | 0.0002 | 0.0002 | 0.0006024 |
+| w1 | 0.0002 | 0.0002 | 0.0006024 |
+| y | 0.0000 | -0.0000 | 3.257e-10 |
+
+Engine values are the probe values after the first sample (zero input) following `reset()`. Nodes the engine does not probe yet show —.
+
+## Figures
+
+### Waveform overlay and error (most demanding signal)
+
+![Waveform overlay and error (most demanding signal)](20261018_b1234_DEFAULT/waveform.png)
+
+### Harmonics
+
+![Harmonics](20261018_b1234_DEFAULT/harmonics.png)
+
+### Magnitude response
+
+![Magnitude response](20261018_b1234_DEFAULT/magnitude.png)
+
+### Spectrogram (DI)
+
+![Spectrogram (DI)](20261018_b1234_DEFAULT/spectrogram.png)
diff --git a/harness/reports/M3/20261018_b1234_DEFAULT/harmonics.png b/harness/reports/M3/20261018_b1234_DEFAULT/harmonics.png
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diff --git a/harness/reports/M3/20261018_b1234_DEFAULT/spectrogram.png b/harness/reports/M3/20261018_b1234_DEFAULT/spectrogram.png
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diff --git a/harness/reports/M3/20261018_b1234_DEFAULT/waveform.png b/harness/reports/M3/20261018_b1234_DEFAULT/waveform.png
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diff --git a/harness/reports/M3/20261018_b1234_knob_jump.md b/harness/reports/M3/20261018_b1234_knob_jump.md
new file mode 100644
index 0000000..3bb6f6c
--- /dev/null
+++ b/harness/reports/M3/20261018_b1234_knob_jump.md
@@ -0,0 +1,14 @@
+# M3 report: B1234 knob-jump test
+
+- Date: 2026-10-18, engine commit `d37baf0 (dirty)`, ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+- Knob targets 0 → 1 in 10 ms from t = 20 ms during a 1000 Hz, 0.1 V tone at the guitar input (DC 0.0000 V); other knobs at their defaults. Engine: smoothing 20 ms, matrix update every 32 samples. SPICE: pot resistances follow the same smoothed trajectory continuously.
+- Window: the ramp and the 20 ms after it. Pass (D-025): no NaN/Inf, ESR ≤ -20 dB.
+
+| Case | Finite | ESR | Status | Peak error / ref peak | Error energy > 5 kHz vs tone |
+|---|---|---|---|---|---|
+| preampVolume | yes | -40.9 dB | PASS | 2.56e-02 | -44.1 dB |
+| treble | yes | -54.2 dB | PASS | 5.45e-03 | -56.8 dB |
+| middle | yes | -50.3 dB | PASS | 5.17e-03 | -57.9 dB |
+| bass | yes | -55.1 dB | PASS | 3.54e-03 | -64.9 dB |
+| master | yes | -41.7 dB | PASS | 7.99e-03 | -46.1 dB |
+| preampVolume+treble+middle+bass+master | yes | -39.1 dB | PASS | 1.16e-02 | -43.4 dB |
diff --git a/harness/reports/M3/20261018_b34_DEFAULT.md b/harness/reports/M3/20261018_b34_DEFAULT.md
new file mode 100644
index 0000000..e541df1
--- /dev/null
+++ b/harness/reports/M3/20261018_b34_DEFAULT.md
@@ -0,0 +1,182 @@
+# M3 report: b34 / DEFAULT
+
+- Block: B34 StageV2aV2bToneStack (B3 + B4 in one tree, D-033)
+- Preset: DEFAULT — Default knobs; standard signal set at the block levels
+- Knobs: preampVolume=0.6, treble=0.5, middle=0.5, bass=0.5, master=0.3, presence=0.5
+- Date: 2026-10-18
+- Engine commit: `d37baf0 (dirty)`
+- Testbench: `harness/testbenches/b34.cir` sha256 `07117b5737acfc59`; netlist sha256 `ffd9b2812204248f`; tubes.lib sha256 `c9c9c88346c69010`
+- ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+
+## Summary
+
+PASS 94 · FAIL 0 · INFO 15 (INFO = measured, not scored in M3)
+
+| Check | Item | Measured | Tolerance | Status |
+|---|---|---|---|---|
+| dc_rel_error | v(bpx) | 0 | ≤ 0.005 | PASS |
+| dc_rel_error | v(g2a) | 0.0006604 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k2a) | 2.495e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k2b) | 1.794e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(mw) | 1.776e-12 | ≤ 0.005 | PASS |
+| dc_rel_error | v(nb) | 0.0006604 | ≤ 0.005 | PASS |
+| dc_rel_error | v(nbb) | 0 | ≤ 0.005 | PASS |
+| dc_rel_error | v(nd) | 1.794e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(ne) | 4.086e-11 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1b) | 1.602e-16 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p2a) | 1.85e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(tt) | 2.132e-11 | ≤ 0.005 | PASS |
+| dc_rel_error | v(tw) | 3.553e-12 | ≤ 0.005 | PASS |
+| dc_rel_error | v(y) | 6.661e-13 | ≤ 0.005 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.1V | -82.13 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.1V | 0.001176 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.1V | 7.992e-06 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.1V | 1 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.1V | -65.33 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.1V | 0.01302 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.1V | 8.693e-05 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.1V | -58.54 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.1V | 0.03089 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.1V | 0.0001545 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-1V | -82.11 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-1V | 0.003703 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-1V | 8.123e-05 pp | — | INFO |
+| newton_failures | SIN-100Hz-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-1V | -65.3 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-1V | 0.01307 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-1V | 0.0008653 pp | — | INFO |
+| newton_failures | SIN-1000Hz-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-1V | -58.5 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-1V | 0.03105 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-1V | 0.00154 pp | — | INFO |
+| newton_failures | SIN-5000Hz-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-10V | -78.5 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-10V | 0.005395 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-10V | 0.002693 pp | — | INFO |
+| newton_failures | SIN-100Hz-10V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-10V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-10V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-10V | -63.53 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-10V | 0.01261 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-10V | 0.001774 pp | — | INFO |
+| newton_failures | SIN-1000Hz-10V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-10V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-10V | 6 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-10V | -57.72 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-10V | 0.02582 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-10V | 0.01119 pp | — | INFO |
+| newton_failures | SIN-5000Hz-10V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-10V | 3 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-10V | 7 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-100Hz-50V | -76.52 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-50V | 0.00116 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-50V | 0.0009068 pp | — | INFO |
+| newton_failures | SIN-100Hz-50V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-50V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-50V | 4 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-1000Hz-50V | -59.44 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-50V | 0.003692 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-50V | 4.422e-05 pp | — | INFO |
+| newton_failures | SIN-1000Hz-50V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-50V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-50V | 7 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-5000Hz-50V | -48.13 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-50V | 0.01608 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-50V | 0.01416 pp | — | INFO |
+| newton_failures | SIN-5000Hz-50V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-50V | 3 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-50V | 7 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-lo-0.1V | -57.59 dB | ≤ -20 | PASS |
+| linear_mag_db_20_10k | SWP-lo-0.1V | 0.01347 dB | ≤ 0.1 | INFO |
+| linear_mag_db_10k_20k | SWP-lo-0.1V | 0.01496 dB | ≤ 0.3 | INFO |
+| method_mag_db_spice_tran_vs_ac | SWP-lo-0.1V | 0.02764 dB | — | INFO |
+| newton_failures | SWP-lo-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-lo-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-lo-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-hi-1V | -57.57 dB | ≤ -20 | PASS |
+| newton_failures | SWP-hi-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-hi-1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-hi-1V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | TT-0.5V | -74.6 dB | ≤ -20 | PASS |
+| newton_failures | TT-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | TT-0.5V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | TT-0.5V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | BURST-10V | -63.52 dB | ≤ -20 | PASS |
+| newton_failures | BURST-10V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | BURST-10V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | BURST-10V | 6 | ≤ 12 | PASS |
+| nonlinear_esr_db | STEP-1V | -72.86 dB | ≤ -20 | PASS |
+| newton_failures | STEP-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | STEP-1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | STEP-1V | 2 | ≤ 12 | PASS |
+
+## Signals
+
+| Signal | Peak F [V] | ESR [dB] | Best lag | ESR at lag [dB] | THD F / E [%] | Power F / E [W] | ns/sample | Newton fail / median / max it |
+|---|---|---|---|---|---|---|---|---|
+| SIN-100Hz-0.1V | 0.04206 | -82.13 | 0 | -82.13 | 0.0456 / 0.0456 | — | 328.2 | 0 / 1 / 1 |
+| SIN-1000Hz-0.1V | 0.03283 | -65.33 | 0 | -65.33 | 0.073 / 0.0731 | — | 330.0 | 0 / 1 / 2 |
+| SIN-5000Hz-0.1V | 0.05907 | -58.54 | 0 | -58.54 | 0.0582 / 0.0584 | — | 479.9 | 0 / 2 / 2 |
+| SIN-100Hz-1V | 0.4183 | -82.11 | 0 | -82.11 | 0.458 / 0.458 | — | 323.5 | 0 / 1 / 2 |
+| SIN-1000Hz-1V | 0.3312 | -65.30 | 0 | -65.30 | 0.73 / 0.731 | — | 462.7 | 0 / 2 / 2 |
+| SIN-5000Hz-1V | 0.5848 | -58.50 | 0 | -58.50 | 0.581 / 0.583 | — | 506.8 | 0 / 2 / 2 |
+| SIN-100Hz-10V | 2.747 | -78.50 | 0 | -78.50 | 10.8 / 10.8 | — | 368.8 | 0 / 1 / 2 |
+| SIN-1000Hz-10V | 1.642 | -63.53 | 0 | -63.53 | 36.8 / 36.8 | — | 507.0 | 0 / 2 / 6 |
+| SIN-5000Hz-10V | 2.381 | -57.72 | 0 | -57.72 | 32.4 / 32.4 | — | 628.1 | 0 / 3 / 7 |
+| SIN-100Hz-50V | 3.15 | -76.52 | 0 | -76.52 | 29.4 / 29.4 | — | 350.8 | 0 / 1 / 4 |
+| SIN-1000Hz-50V | 2.419 | -59.44 | 0 | -59.44 | 67.2 / 67.2 | — | 484.0 | 0 / 2 / 7 |
+| SIN-5000Hz-50V | 2.527 | -48.13 | 0 | -48.13 | 55.6 / 55.6 | — | 611.2 | 0 / 3 / 7 |
+| SWP-lo-0.1V | 0.05772 | -57.59 | 0 | -57.59 | — | — | 378.9 | 0 / 1 / 2 |
+| SWP-hi-1V | 0.5784 | -57.57 | 0 | -57.57 | — | — | 408.8 | 0 / 1 / 3 |
+| TT-0.5V | 0.318 | -74.60 | 0 | -74.60 | — | — | 324.9 | 0 / 1 / 2 |
+| BURST-10V | 1.64 | -63.52 | 0 | -63.52 | — | — | 424.5 | 0 / 1 / 6 |
+| STEP-1V | 0.621 | -72.86 | 0 | -72.86 | — | — | 332.6 | 0 / 1 / 2 |
+
+## DC operating point
+
+| Node | SPICE [V] | Engine [V] | Rel. error |
+|---|---|---|---|
+| bpx | 404.9982 | 404.9982 | 0 |
+| g2a | 0.0005 | 0.0005 | 0.0006604 |
+| k2a | 1.4139 | 1.4138 | 2.495e-05 |
+| k2b | 233.1404 | 233.1446 | 1.794e-05 |
+| mw | 0.0000 | 0.0000 | 1.776e-12 |
+| nb | 0.0005 | 0.0005 | 0.0006604 |
+| nbb | 0.0000 | 0.0000 | 0 |
+| nd | 233.1404 | 233.1446 | 1.794e-05 |
+| ne | 0.0000 | -0.0000 | 4.086e-11 |
+| p1b | 354.7502 | 354.7502 | 1.602e-16 |
+| p2a | 232.5771 | 232.5814 | 1.85e-05 |
+| tt | 0.0000 | 0.0000 | 2.132e-11 |
+| tw | 0.0000 | -0.0000 | 3.553e-12 |
+| y | 0.0000 | 0.0000 | 6.661e-13 |
+
+Engine values are the probe values after the first sample (zero input) following `reset()`. Nodes the engine does not probe yet show —.
+
+## Figures
+
+### Waveform overlay and error (most demanding signal)
+
+![Waveform overlay and error (most demanding signal)](20261018_b34_DEFAULT/waveform.png)
+
+### Harmonics
+
+![Harmonics](20261018_b34_DEFAULT/harmonics.png)
+
+### Magnitude response
+
+![Magnitude response](20261018_b34_DEFAULT/magnitude.png)
diff --git a/harness/reports/M3/20261018_b34_DEFAULT/harmonics.png b/harness/reports/M3/20261018_b34_DEFAULT/harmonics.png
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diff --git a/harness/reports/M3/20261018_b34_DEFAULT/magnitude.png b/harness/reports/M3/20261018_b34_DEFAULT/magnitude.png
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diff --git a/harness/reports/M3/20261018_b34_DEFAULT/waveform.png b/harness/reports/M3/20261018_b34_DEFAULT/waveform.png
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diff --git a/harness/reports/M3/20261018_b34_knob_jump.md b/harness/reports/M3/20261018_b34_knob_jump.md
new file mode 100644
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--- /dev/null
+++ b/harness/reports/M3/20261018_b34_knob_jump.md
@@ -0,0 +1,13 @@
+# M3 report: B34 knob-jump test
+
+- Date: 2026-10-18, engine commit `d37baf0 (dirty)`, ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+- Knob targets 0 → 1 in 10 ms from t = 20 ms during a 1000 Hz, 1 V tone on the J2 DC level (DC 354.7502 V); other knobs at their defaults. Engine: smoothing 20 ms, matrix update every 32 samples. SPICE: pot resistances follow the same smoothed trajectory continuously.
+- Window: the ramp and the 20 ms after it. Pass (D-025): no NaN/Inf, ESR ≤ -20 dB.
+
+| Case | Finite | ESR | Status | Peak error / ref peak | Error energy > 5 kHz vs tone |
+|---|---|---|---|---|---|
+| treble | yes | -67.6 dB | PASS | 1.04e-03 | -68.4 dB |
+| middle | yes | -64.2 dB | PASS | 1.03e-03 | -72.4 dB |
+| bass | yes | -62.9 dB | PASS | 9.12e-04 | -109.9 dB |
+| master | yes | -54.1 dB | PASS | 2.47e-03 | -56.1 dB |
+| treble+middle+bass+master | yes | -53.1 dB | PASS | 2.89e-03 | -54.8 dB |
diff --git a/harness/reports/M3/20261018_b3_DEFAULT.md b/harness/reports/M3/20261018_b3_DEFAULT.md
new file mode 100644
index 0000000..62d9d4f
--- /dev/null
+++ b/harness/reports/M3/20261018_b3_DEFAULT.md
@@ -0,0 +1,168 @@
+# M3 report: b3 / DEFAULT
+
+- Block: B3 StageV2aV2b
+- Preset: DEFAULT — Default knobs; standard signal set at the block levels
+- Knobs: preampVolume=0.6, treble=0.5, middle=0.5, bass=0.5, master=0.3, presence=0.5
+- Date: 2026-10-18
+- Engine commit: `d37baf0 (dirty)`
+- Testbench: `harness/testbenches/b3.cir` sha256 `7e2f0a59288617d9`; netlist sha256 `ffd9b2812204248f`; tubes.lib sha256 `c9c9c88346c69010`
+- ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+
+## Summary
+
+PASS 87 · FAIL 0 · INFO 15 (INFO = measured, not scored in M3)
+
+| Check | Item | Measured | Tolerance | Status |
+|---|---|---|---|---|
+| dc_rel_error | v(bpx) | 0 | ≤ 0.005 | PASS |
+| dc_rel_error | v(g2a) | 0.0006604 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k2a) | 2.495e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(k2b) | 1.794e-05 | ≤ 0.005 | PASS |
+| dc_rel_error | v(nb) | 0.0006604 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p1b) | 1.602e-16 | ≤ 0.005 | PASS |
+| dc_rel_error | v(p2a) | 1.85e-05 | ≤ 0.005 | PASS |
+| nonlinear_esr_db | SIN-100Hz-0.1V | -82.22 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-0.1V | 0.001141 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-0.1V | 8.687e-06 pp | — | INFO |
+| newton_failures | SIN-100Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-0.1V | 1 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-0.1V | -65.4 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-0.1V | 0.01272 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-0.1V | 6.728e-05 pp | — | INFO |
+| newton_failures | SIN-1000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-0.1V | -58.58 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-0.1V | 0.03003 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-0.1V | 0.0001551 pp | — | INFO |
+| newton_failures | SIN-5000Hz-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-0.1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-1V | -82.19 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-1V | 0.003423 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-1V | 8.843e-05 pp | — | INFO |
+| newton_failures | SIN-100Hz-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-1V | -65.38 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-1V | 0.01281 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-1V | 0.0006782 pp | — | INFO |
+| newton_failures | SIN-1000Hz-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-1V | -58.54 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-1V | 0.031 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-1V | 0.00162 pp | — | INFO |
+| newton_failures | SIN-5000Hz-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-1V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-100Hz-10V | -80.18 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-10V | 0.01487 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-10V | 0.0009158 pp | — | INFO |
+| newton_failures | SIN-100Hz-10V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-10V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-10V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-1000Hz-10V | -65.85 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-10V | 0.01237 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-10V | 0.004707 pp | — | INFO |
+| newton_failures | SIN-1000Hz-10V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-10V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-10V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | SIN-5000Hz-10V | -59.93 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-10V | 0.01483 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-10V | 0.01898 pp | — | INFO |
+| newton_failures | SIN-5000Hz-10V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-10V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-10V | 4 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-100Hz-50V | -76.63 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-100Hz-50V | 0.001125 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-100Hz-50V | 0.0003032 pp | — | INFO |
+| newton_failures | SIN-100Hz-50V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-100Hz-50V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-100Hz-50V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-1000Hz-50V | -64.03 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-1000Hz-50V | 0.00263 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-1000Hz-50V | 0.0009813 pp | — | INFO |
+| newton_failures | SIN-1000Hz-50V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-1000Hz-50V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-1000Hz-50V | 4 | ≤ 12 | PASS |
+| nonlinear_esr_db_overdrive | SIN-5000Hz-50V | -54.24 dB | ≤ -20 | PASS |
+| harmonics_2_5_db | SIN-5000Hz-50V | 0.004271 dB | ≤ 0.5 | PASS |
+| thd_pp | SIN-5000Hz-50V | 0.0137 pp | — | INFO |
+| newton_failures | SIN-5000Hz-50V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SIN-5000Hz-50V | 2 | ≤ 3 | PASS |
+| newton_max_iterations | SIN-5000Hz-50V | 5 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-lo-0.1V | -58.73 dB | ≤ -20 | PASS |
+| linear_mag_db_20_10k | SWP-lo-0.1V | 0.01374 dB | ≤ 0.1 | INFO |
+| linear_mag_db_10k_20k | SWP-lo-0.1V | 0.01517 dB | ≤ 0.3 | INFO |
+| method_mag_db_spice_tran_vs_ac | SWP-lo-0.1V | 0.02799 dB | — | INFO |
+| newton_failures | SWP-lo-0.1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-lo-0.1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-lo-0.1V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | SWP-hi-1V | -58.7 dB | ≤ -20 | PASS |
+| newton_failures | SWP-hi-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | SWP-hi-1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | SWP-hi-1V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | TT-0.5V | -74.27 dB | ≤ -20 | PASS |
+| newton_failures | TT-0.5V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | TT-0.5V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | TT-0.5V | 2 | ≤ 12 | PASS |
+| nonlinear_esr_db | BURST-10V | -65.85 dB | ≤ -20 | PASS |
+| newton_failures | BURST-10V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | BURST-10V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | BURST-10V | 3 | ≤ 12 | PASS |
+| nonlinear_esr_db | STEP-1V | -73.14 dB | ≤ -20 | PASS |
+| newton_failures | STEP-1V | 0 | ≤ 0 | PASS |
+| newton_median_iterations | STEP-1V | 1 | ≤ 3 | PASS |
+| newton_max_iterations | STEP-1V | 2 | ≤ 12 | PASS |
+
+## Signals
+
+| Signal | Peak F [V] | ESR [dB] | Best lag | ESR at lag [dB] | THD F / E [%] | Power F / E [W] | ns/sample | Newton fail / median / max it |
+|---|---|---|---|---|---|---|---|---|
+| SIN-100Hz-0.1V | 2.04 | -82.22 | 0 | -82.22 | 0.051 / 0.051 | — | 305.3 | 0 / 1 / 1 |
+| SIN-1000Hz-0.1V | 2.497 | -65.40 | 0 | -65.40 | 0.0581 / 0.0582 | — | 300.9 | 0 / 1 / 2 |
+| SIN-5000Hz-0.1V | 3.013 | -58.58 | 0 | -58.58 | 0.0603 / 0.0605 | — | 450.1 | 0 / 2 / 2 |
+| SIN-100Hz-1V | 20.19 | -82.19 | 0 | -82.19 | 0.511 / 0.511 | — | 293.5 | 0 / 1 / 2 |
+| SIN-1000Hz-1V | 25.12 | -65.38 | 0 | -65.38 | 0.583 / 0.584 | — | 403.5 | 0 / 2 / 2 |
+| SIN-5000Hz-1V | 29.73 | -58.54 | 0 | -58.54 | 0.606 / 0.608 | — | 460.7 | 0 / 2 / 2 |
+| SIN-100Hz-10V | 127.9 | -80.18 | 0 | -80.18 | 14.3 / 14.3 | — | 334.1 | 0 / 1 / 2 |
+| SIN-1000Hz-10V | 130.3 | -65.85 | 0 | -65.85 | 19 / 19 | — | 492.5 | 0 / 2 / 3 |
+| SIN-5000Hz-10V | 130.4 | -59.93 | 0 | -59.93 | 28 / 28 | — | 545.9 | 0 / 2 / 4 |
+| SIN-100Hz-50V | 130.3 | -76.63 | 0 | -76.63 | 40.1 / 40.1 | — | 329.8 | 0 / 1 / 3 |
+| SIN-1000Hz-50V | 139.5 | -64.03 | 0 | -64.03 | 45.5 / 45.5 | — | 397.7 | 0 / 2 / 4 |
+| SIN-5000Hz-50V | 163.6 | -54.24 | 0 | -54.24 | 54.9 / 54.9 | — | 492.0 | 0 / 2 / 5 |
+| SWP-lo-0.1V | 2.938 | -58.73 | 0 | -58.73 | — | — | 344.6 | 0 / 1 / 2 |
+| SWP-hi-1V | 29.71 | -58.70 | 0 | -58.70 | — | — | 362.6 | 0 / 1 / 3 |
+| TT-0.5V | 19.5 | -74.27 | 0 | -74.27 | — | — | 292.9 | 0 / 1 / 2 |
+| BURST-10V | 130.3 | -65.85 | 0 | -65.85 | — | — | 378.9 | 0 / 1 / 3 |
+| STEP-1V | 30.83 | -73.14 | 0 | -73.14 | — | — | 294.0 | 0 / 1 / 2 |
+
+## DC operating point
+
+| Node | SPICE [V] | Engine [V] | Rel. error |
+|---|---|---|---|
+| bpx | 404.9982 | 404.9982 | 0 |
+| g2a | 0.0005 | 0.0005 | 0.0006604 |
+| k2a | 1.4139 | 1.4138 | 2.495e-05 |
+| k2b | 233.1404 | 233.1446 | 1.794e-05 |
+| nb | 0.0005 | 0.0005 | 0.0006604 |
+| p1b | 354.7502 | 354.7502 | 1.602e-16 |
+| p2a | 232.5771 | 232.5814 | 1.85e-05 |
+
+Engine values are the probe values after the first sample (zero input) following `reset()`. Nodes the engine does not probe yet show —.
+
+## Figures
+
+### Waveform overlay and error (most demanding signal)
+
+![Waveform overlay and error (most demanding signal)](20261018_b3_DEFAULT/waveform.png)
+
+### Harmonics
+
+![Harmonics](20261018_b3_DEFAULT/harmonics.png)
+
+### Magnitude response
+
+![Magnitude response](20261018_b3_DEFAULT/magnitude.png)
diff --git a/harness/reports/M3/20261018_b3_DEFAULT/harmonics.png b/harness/reports/M3/20261018_b3_DEFAULT/harmonics.png
new file mode 100644
index 0000000..71cda0d
Binary files /dev/null and b/harness/reports/M3/20261018_b3_DEFAULT/harmonics.png differ
diff --git a/harness/reports/M3/20261018_b3_DEFAULT/magnitude.png b/harness/reports/M3/20261018_b3_DEFAULT/magnitude.png
new file mode 100644
index 0000000..27a85a4
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diff --git a/harness/reports/M3/20261018_b3_DEFAULT/waveform.png b/harness/reports/M3/20261018_b3_DEFAULT/waveform.png
new file mode 100644
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diff --git a/harness/reports/M4/20261018_full_acceptance.md b/harness/reports/M4/20261018_full_acceptance.md
index 2a5e713..992d414 100644
--- a/harness/reports/M4/20261018_full_acceptance.md
+++ b/harness/reports/M4/20261018_full_acceptance.md
@@ -1,7 +1,7 @@
 # M4 acceptance: full amplifier vs the full netlist
 
-- Date: 2026-10-18, engine commit `9a422dd (dirty)`, ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
-- Netlist sha256 `83f01b6fd8b64a06`, tubes.lib sha256 `c9c9c88346c69010`
+- Date: 2026-10-18, engine commit `d37baf0 (dirty)`, ngspice 47, fs = 768000 Hz, SPICE reltol 1e-08
+- Netlist sha256 `ffd9b2812204248f`, tubes.lib sha256 `c9c9c88346c69010`
 - Engine: `ampwav --block full` (volts at the jack and across the 16 Ω load), the checks of SPEC §7 M4.
 
 ## Summary
@@ -38,90 +38,90 @@ PASS 107 · FAIL 0
 | nfb | newton_unrescued | closed 100 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | closed 100 Hz | 1 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | closed 100 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | closed 1000 Hz | 0.005358 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | closed 1000 Hz | 0.00536 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | closed 1000 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | closed 1000 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | closed 1000 Hz | 1 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | closed 1000 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | closed 5000 Hz | 0.01505 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | closed 5000 Hz | 0.01479 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | closed 5000 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | closed 5000 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | closed 5000 Hz | 2 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | closed 5000 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | open 100 Hz | 0.002271 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | open 100 Hz | 0.00227 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | open 100 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | open 100 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | open 100 Hz | 1 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | open 100 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | open 1000 Hz | 0.007852 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | open 1000 Hz | 0.007856 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | open 1000 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | open 1000 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | open 1000 Hz | 1 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | open 1000 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | open 5000 Hz | 0.0599 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | open 5000 Hz | 0.05701 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | open 5000 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | open 5000 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | open 5000 Hz | 2 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | open 5000 Hz | 2 | ≤ 32 | PASS |
 | clean | total_esr_db | CLEAN SIN-1000Hz-0.025V | -30.3 dB | ≤ -20 | PASS |
-| clean | total_harmonics_2_9_db | CLEAN SIN-1000Hz-0.025V | 0.8439 dB | ≤ 1.5 | PASS |
+| clean | total_harmonics_2_9_db | CLEAN SIN-1000Hz-0.025V | 0.7255 dB | ≤ 1.5 | PASS |
 | clean | newton_failures | CLEAN SIN-1000Hz-0.025V | 0 | ≤ 0 | PASS |
 | clean | newton_unrescued | CLEAN SIN-1000Hz-0.025V | 0 | — | INFO |
 | clean | newton_median_iterations | CLEAN SIN-1000Hz-0.025V | 2 | ≤ 3 | PASS |
-| clean | newton_max_iterations | CLEAN SIN-1000Hz-0.025V | 5 | ≤ 32 | PASS |
-| clean | total_power_rel | CLEAN SIN-1000Hz-0.025V | 0.03926 | ≤ 0.05 | PASS |
-| clean | total_thd_pp | CLEAN SIN-1000Hz-0.025V | 0.2177 pp | ≤ 0.5 | PASS |
-| stability | stability_out_v | max |out| | 4.355e-05 V | ≤ 0.001 | PASS |
-| stability | stability_growth | RMS last 10 s − first 10 s | 4.006e-13 V | ≤ 1e-06 | PASS |
+| clean | newton_max_iterations | CLEAN SIN-1000Hz-0.025V | 3 | ≤ 32 | PASS |
+| clean | total_power_rel | CLEAN SIN-1000Hz-0.025V | 0.03927 | ≤ 0.05 | PASS |
+| clean | total_thd_pp | CLEAN SIN-1000Hz-0.025V | 0.2173 pp | ≤ 0.5 | PASS |
+| stability | stability_out_v | max |out| | 4.267e-05 V | ≤ 0.001 | PASS |
+| stability | stability_growth | RMS last 10 s − first 10 s | 8.08e-12 V | ≤ 1e-06 | PASS |
 | stability | newton_failures | 60 s silence | 0 | ≤ 0 | PASS |
 | stability | newton_unrescued | 60 s silence | 0 | — | INFO |
 | stability | newton_median_iterations | 60 s silence | 1 | ≤ 3 | PASS |
 | stability | newton_max_iterations | 60 s silence | 1 | ≤ 32 | PASS |
-| overdrive | total_esr_db | OVERDRIVE SIN-220Hz-0.3V | -68.01 dB | ≤ -20 | PASS |
-| overdrive | total_harmonics_2_9_db | OVERDRIVE SIN-220Hz-0.3V | 0.008618 dB | ≤ 1.5 | PASS |
-| overdrive | sag_min_v | OVERDRIVE SIN-220Hz-0.3V | 0.003538 V | ≤ 2 | PASS |
+| overdrive | total_esr_db | OVERDRIVE SIN-220Hz-0.3V | -67.99 dB | ≤ -20 | PASS |
+| overdrive | total_harmonics_2_9_db | OVERDRIVE SIN-220Hz-0.3V | 0.008614 dB | ≤ 1.5 | PASS |
+| overdrive | sag_min_v | OVERDRIVE SIN-220Hz-0.3V | 0.003537 V | ≤ 2 | PASS |
 | overdrive | newton_failures | OVERDRIVE SIN-220Hz-0.3V | 0 | ≤ 0 | PASS |
 | overdrive | newton_unrescued | OVERDRIVE SIN-220Hz-0.3V | 0 | — | INFO |
 | overdrive | newton_median_iterations | OVERDRIVE SIN-220Hz-0.3V | 1 | ≤ 3 | PASS |
 | overdrive | newton_max_iterations | OVERDRIVE SIN-220Hz-0.3V | 5 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH SIN-220Hz-0.3V | -70.27 dB | ≤ -20 | PASS |
-| crunch_drive | total_harmonics_2_9_db | CRUNCH SIN-220Hz-0.3V | 0.00792 dB | ≤ 1.5 | PASS |
+| crunch_drive | total_esr_db | CRUNCH SIN-220Hz-0.3V | -70.25 dB | ≤ -20 | PASS |
+| crunch_drive | total_harmonics_2_9_db | CRUNCH SIN-220Hz-0.3V | 0.007954 dB | ≤ 1.5 | PASS |
 | crunch_drive | newton_failures | CRUNCH SIN-220Hz-0.3V | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH SIN-220Hz-0.3V | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH SIN-220Hz-0.3V | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | CRUNCH SIN-220Hz-0.3V | 5 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH DI-GTR L | -60.76 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | CRUNCH DI-GTR L | -60.8 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | CRUNCH DI-GTR L | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH DI-GTR L | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH DI-GTR L | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | CRUNCH DI-GTR L | 7 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH DI-GTR LL | -61.31 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | CRUNCH DI-GTR LL | -61.36 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | CRUNCH DI-GTR LL | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH DI-GTR LL | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH DI-GTR LL | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | CRUNCH DI-GTR LL | 7 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH DI-GTR R | -62.06 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | CRUNCH DI-GTR R | -62.11 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | CRUNCH DI-GTR R | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH DI-GTR R | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH DI-GTR R | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | CRUNCH DI-GTR R | 7 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH DI-GTR RR | -60.9 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | CRUNCH DI-GTR RR | -60.94 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | CRUNCH DI-GTR RR | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH DI-GTR RR | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH DI-GTR RR | 2 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | CRUNCH DI-GTR RR | 9 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE SIN-220Hz-0.3V | -63.51 dB | ≤ -20 | PASS |
-| crunch_drive | total_harmonics_2_9_db | DRIVE SIN-220Hz-0.3V | 0.03181 dB | ≤ 1.5 | PASS |
+| crunch_drive | newton_max_iterations | CRUNCH DI-GTR RR | 7 | ≤ 32 | PASS |
+| crunch_drive | total_esr_db | DRIVE SIN-220Hz-0.3V | -63.49 dB | ≤ -20 | PASS |
+| crunch_drive | total_harmonics_2_9_db | DRIVE SIN-220Hz-0.3V | 0.03171 dB | ≤ 1.5 | PASS |
 | crunch_drive | newton_failures | DRIVE SIN-220Hz-0.3V | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE SIN-220Hz-0.3V | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE SIN-220Hz-0.3V | 1 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | DRIVE SIN-220Hz-0.3V | 5 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE DI-GTR L | -60.26 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | DRIVE DI-GTR L | -60.24 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | DRIVE DI-GTR L | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE DI-GTR L | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE DI-GTR L | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | DRIVE DI-GTR L | 7 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE DI-GTR LL | -61.53 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | DRIVE DI-GTR LL | -61.54 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | DRIVE DI-GTR LL | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE DI-GTR LL | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE DI-GTR LL | 2 | ≤ 3 | PASS |
@@ -131,11 +131,11 @@ PASS 107 · FAIL 0
 | crunch_drive | newton_unrescued | DRIVE DI-GTR R | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE DI-GTR R | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | DRIVE DI-GTR R | 7 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE DI-GTR RR | -60.29 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | DRIVE DI-GTR RR | -60.27 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | DRIVE DI-GTR RR | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE DI-GTR RR | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE DI-GTR RR | 2 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | DRIVE DI-GTR RR | 7 | ≤ 32 | PASS |
+| crunch_drive | newton_max_iterations | DRIVE DI-GTR RR | 8 | ≤ 32 | PASS |
 
 ## DC operating point
 
@@ -167,30 +167,30 @@ PASS 107 · FAIL 0
 
 | f | SPICE closed | engine closed | SPICE open | engine open | NFB SPICE | NFB engine |
 |---|---|---|---|---|---|---|
-| 100 Hz | 45.92 | 45.92 | 56.34 | 56.34 | 10.42 | 10.42 |
-| 1000 Hz | 53.54 | 53.54 | 57.85 | 57.86 | 4.32 | 4.32 |
-| 5000 Hz | 69.86 | 69.88 | 77.77 | 77.83 | 7.91 | 7.95 |
+| 100 Hz | 45.93 | 45.93 | 56.34 | 56.34 | 10.42 | 10.42 |
+| 1000 Hz | 53.54 | 53.55 | 57.86 | 57.86 | 4.32 | 4.32 |
+| 5000 Hz | 69.59 | 69.61 | 77.50 | 77.55 | 7.91 | 7.95 |
 
 ## Signals
 
 | Preset | Signal | ESR | best lag | harm. 2–9 | THD F / E | Power F / E | min v(ct) F / E |
 |---|---|---|---|---|---|---|---|
-| CLEAN | SIN-1000Hz-0.025V | -30.3 dB | 2 | 0.84 dB | 7.37 / 7.59 % | 81.1 / 78.0 W | — |
-| OVERDRIVE | SIN-220Hz-0.3V | -68.0 dB | 0 | 0.01 dB | 19.61 / 19.61 % | 32.2 / 32.2 W | 474.38 / 474.37 V |
-| CRUNCH | SIN-220Hz-0.3V | -70.3 dB | 0 | 0.01 dB | 12.00 / 12.00 % | 31.6 / 31.6 W | — |
+| CLEAN | SIN-1000Hz-0.025V | -30.3 dB | 2 | 0.73 dB | 7.37 / 7.59 % | 81.1 / 77.9 W | — |
+| OVERDRIVE | SIN-220Hz-0.3V | -68.0 dB | 0 | 0.01 dB | 19.62 / 19.62 % | 32.2 / 32.2 W | 474.38 / 474.37 V |
+| CRUNCH | SIN-220Hz-0.3V | -70.3 dB | 0 | 0.01 dB | 12.01 / 12.01 % | 31.6 / 31.6 W | — |
 | CRUNCH | DI-GTR L | -60.8 dB | 0 | — | — | — | — |
-| CRUNCH | DI-GTR LL | -61.3 dB | 0 | — | — | — | — |
+| CRUNCH | DI-GTR LL | -61.4 dB | 0 | — | — | — | — |
 | CRUNCH | DI-GTR R | -62.1 dB | 0 | — | — | — | — |
 | CRUNCH | DI-GTR RR | -60.9 dB | 0 | — | — | — | — |
-| DRIVE | SIN-220Hz-0.3V | -63.5 dB | 0 | 0.03 dB | 22.53 / 22.53 % | 34.5 / 34.5 W | — |
-| DRIVE | DI-GTR L | -60.3 dB | 0 | — | — | — | — |
+| DRIVE | SIN-220Hz-0.3V | -63.5 dB | 0 | 0.03 dB | 22.53 / 22.53 % | 34.5 / 34.6 W | — |
+| DRIVE | DI-GTR L | -60.2 dB | 0 | — | — | — | — |
 | DRIVE | DI-GTR LL | -61.5 dB | 0 | — | — | — | — |
 | DRIVE | DI-GTR R | -61.0 dB | 0 | — | — | — | — |
 | DRIVE | DI-GTR RR | -60.3 dB | 0 | — | — | — | — |
 
 ## Stability
 
-60 s silence at Preamp / Master / Presence 1.0: max |out| 4.36e-05 V, RMS first / last 10 s 4.24e-05 / 4.24e-05 V.
+60 s silence at Preamp / Master / Presence 1.0: max |out| 4.27e-05 V, RMS first / last 10 s 4.24e-05 / 4.24e-05 V.
 
 ## Delayed-NFB break
 
diff --git a/harness/reports/M6/20261018_auval.log b/harness/reports/M6/20261018_auval.log
index 78ae3db..c8eb1a9 100644
--- a/harness/reports/M6/20261018_auval.log
+++ b/harness/reports/M6/20261018_auval.log
@@ -15,12 +15,12 @@ Component Version: 0.0.1 (0x1)
 --------------------------------------------------
 TESTING OPEN TIMES:
 COLD:
-Time to open AudioUnit:         10.250 ms
+Time to open AudioUnit:         10.234 ms
 WARM:
-Time to open AudioUnit:         5.935  ms
+Time to open AudioUnit:         6.247  ms
 This AudioUnit is a version 2 implementation.
 FIRST TIME:
-Time for initialization:        9.994 ms
+Time for initialization:        10.030 ms
 
 * * PASS
 --------------------------------------------------
@@ -65,7 +65,7 @@ VERIFYING SPECIAL PROPERTIES:
 
 VERIFYING CUSTOM UI
 Cocoa Views Available: 1
-  JUCE_AUCocoaViewClass_387eba94ef07be2a
+  JUCE_AUCocoaViewClass_a0ff1c23697f1de4
     PASS
 
 HAS FACTORY PRESETS
diff --git a/harness/reports/M6/20261018_full_acceptance_fs384000_j4exact.md b/harness/reports/M6/20261018_full_acceptance_fs384000_j4exact.md
index b37c301..167d538 100644
--- a/harness/reports/M6/20261018_full_acceptance_fs384000_j4exact.md
+++ b/harness/reports/M6/20261018_full_acceptance_fs384000_j4exact.md
@@ -1,7 +1,7 @@
 # M4 acceptance: full amplifier vs the full netlist
 
-- Date: 2026-10-18, engine commit `9a422dd (dirty)`, ngspice 47, fs = 384000 Hz, J4 exact, SPICE reltol 1e-08
-- Netlist sha256 `83f01b6fd8b64a06`, tubes.lib sha256 `c9c9c88346c69010`
+- Date: 2026-10-18, engine commit `d37baf0 (dirty)`, ngspice 47, fs = 384000 Hz, J4 exact, SPICE reltol 1e-08
+- Netlist sha256 `ffd9b2812204248f`, tubes.lib sha256 `c9c9c88346c69010`
 - Engine: `ampwav --block full` (volts at the jack and across the 16 Ω load), the checks of SPEC §7 M4.
 
 ## Summary
@@ -38,12 +38,12 @@ PASS 107 · FAIL 0
 | nfb | newton_unrescued | closed 100 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | closed 100 Hz | 1 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | closed 100 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | closed 1000 Hz | 0.00581 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | closed 1000 Hz | 0.005811 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | closed 1000 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | closed 1000 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | closed 1000 Hz | 1 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | closed 1000 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | closed 5000 Hz | 0.01713 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | closed 5000 Hz | 0.01669 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | closed 5000 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | closed 5000 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | closed 5000 Hz | 2 | ≤ 3 | PASS |
@@ -53,89 +53,89 @@ PASS 107 · FAIL 0
 | nfb | newton_unrescued | open 100 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | open 100 Hz | 1 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | open 100 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | open 1000 Hz | 0.008418 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | open 1000 Hz | 0.008421 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | open 1000 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | open 1000 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | open 1000 Hz | 1 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | open 1000 Hz | 2 | ≤ 32 | PASS |
-| nfb | nfb_gain_db | open 5000 Hz | 0.06358 dB | ≤ 0.5 | PASS |
+| nfb | nfb_gain_db | open 5000 Hz | 0.06051 dB | ≤ 0.5 | PASS |
 | nfb | newton_failures | open 5000 Hz | 0 | ≤ 0 | PASS |
 | nfb | newton_unrescued | open 5000 Hz | 0 | — | INFO |
 | nfb | newton_median_iterations | open 5000 Hz | 2 | ≤ 3 | PASS |
 | nfb | newton_max_iterations | open 5000 Hz | 2 | ≤ 32 | PASS |
-| clean | total_esr_db | CLEAN SIN-1000Hz-0.025V | -59.66 dB | ≤ -20 | PASS |
-| clean | total_harmonics_2_9_db | CLEAN SIN-1000Hz-0.025V | 0.02005 dB | ≤ 1.5 | PASS |
+| clean | total_esr_db | CLEAN SIN-1000Hz-0.025V | -59.65 dB | ≤ -20 | PASS |
+| clean | total_harmonics_2_9_db | CLEAN SIN-1000Hz-0.025V | 0.02006 dB | ≤ 1.5 | PASS |
 | clean | newton_failures | CLEAN SIN-1000Hz-0.025V | 0 | ≤ 0 | PASS |
 | clean | newton_unrescued | CLEAN SIN-1000Hz-0.025V | 0 | — | INFO |
 | clean | newton_median_iterations | CLEAN SIN-1000Hz-0.025V | 2 | ≤ 3 | PASS |
-| clean | newton_max_iterations | CLEAN SIN-1000Hz-0.025V | 5 | ≤ 32 | PASS |
+| clean | newton_max_iterations | CLEAN SIN-1000Hz-0.025V | 6 | ≤ 32 | PASS |
 | clean | total_power_rel | CLEAN SIN-1000Hz-0.025V | 0.001223 | ≤ 0.05 | PASS |
-| clean | total_thd_pp | CLEAN SIN-1000Hz-0.025V | 0.0004268 pp | ≤ 0.5 | PASS |
-| stability | stability_out_v | max |out| | 4.853e-05 V | ≤ 0.001 | PASS |
-| stability | stability_growth | RMS last 10 s − first 10 s | 5.72e-12 V | ≤ 1e-06 | PASS |
+| clean | total_thd_pp | CLEAN SIN-1000Hz-0.025V | 0.0004352 pp | ≤ 0.5 | PASS |
+| stability | stability_out_v | max |out| | 4.546e-05 V | ≤ 0.001 | PASS |
+| stability | stability_growth | RMS last 10 s − first 10 s | 7.426e-12 V | ≤ 1e-06 | PASS |
 | stability | newton_failures | 60 s silence | 0 | ≤ 0 | PASS |
 | stability | newton_unrescued | 60 s silence | 0 | — | INFO |
 | stability | newton_median_iterations | 60 s silence | 1 | ≤ 3 | PASS |
 | stability | newton_max_iterations | 60 s silence | 1 | ≤ 32 | PASS |
-| overdrive | total_esr_db | OVERDRIVE SIN-220Hz-0.3V | -67.51 dB | ≤ -20 | PASS |
-| overdrive | total_harmonics_2_9_db | OVERDRIVE SIN-220Hz-0.3V | 0.009061 dB | ≤ 1.5 | PASS |
+| overdrive | total_esr_db | OVERDRIVE SIN-220Hz-0.3V | -67.5 dB | ≤ -20 | PASS |
+| overdrive | total_harmonics_2_9_db | OVERDRIVE SIN-220Hz-0.3V | 0.009058 dB | ≤ 1.5 | PASS |
 | overdrive | sag_min_v | OVERDRIVE SIN-220Hz-0.3V | 0.003903 V | ≤ 2 | PASS |
 | overdrive | newton_failures | OVERDRIVE SIN-220Hz-0.3V | 0 | ≤ 0 | PASS |
 | overdrive | newton_unrescued | OVERDRIVE SIN-220Hz-0.3V | 0 | — | INFO |
 | overdrive | newton_median_iterations | OVERDRIVE SIN-220Hz-0.3V | 2 | ≤ 3 | PASS |
 | overdrive | newton_max_iterations | OVERDRIVE SIN-220Hz-0.3V | 6 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH SIN-220Hz-0.3V | -69.67 dB | ≤ -20 | PASS |
-| crunch_drive | total_harmonics_2_9_db | CRUNCH SIN-220Hz-0.3V | 0.008084 dB | ≤ 1.5 | PASS |
+| crunch_drive | total_esr_db | CRUNCH SIN-220Hz-0.3V | -69.66 dB | ≤ -20 | PASS |
+| crunch_drive | total_harmonics_2_9_db | CRUNCH SIN-220Hz-0.3V | 0.008117 dB | ≤ 1.5 | PASS |
 | crunch_drive | newton_failures | CRUNCH SIN-220Hz-0.3V | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH SIN-220Hz-0.3V | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH SIN-220Hz-0.3V | 1 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | CRUNCH SIN-220Hz-0.3V | 5 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH DI-GTR L | -59.59 dB | ≤ -20 | PASS |
+| crunch_drive | newton_max_iterations | CRUNCH SIN-220Hz-0.3V | 4 | ≤ 32 | PASS |
+| crunch_drive | total_esr_db | CRUNCH DI-GTR L | -59.73 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | CRUNCH DI-GTR L | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH DI-GTR L | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH DI-GTR L | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | CRUNCH DI-GTR L | 8 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH DI-GTR LL | -59.82 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | CRUNCH DI-GTR LL | -60.06 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | CRUNCH DI-GTR LL | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH DI-GTR LL | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH DI-GTR LL | 2 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | CRUNCH DI-GTR LL | 8 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH DI-GTR R | -60.79 dB | ≤ -20 | PASS |
+| crunch_drive | newton_max_iterations | CRUNCH DI-GTR LL | 7 | ≤ 32 | PASS |
+| crunch_drive | total_esr_db | CRUNCH DI-GTR R | -60.65 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | CRUNCH DI-GTR R | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH DI-GTR R | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH DI-GTR R | 2 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | CRUNCH DI-GTR R | 8 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | CRUNCH DI-GTR RR | -59.38 dB | ≤ -20 | PASS |
+| crunch_drive | newton_max_iterations | CRUNCH DI-GTR R | 7 | ≤ 32 | PASS |
+| crunch_drive | total_esr_db | CRUNCH DI-GTR RR | -59.5 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | CRUNCH DI-GTR RR | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | CRUNCH DI-GTR RR | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | CRUNCH DI-GTR RR | 2 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | CRUNCH DI-GTR RR | 11 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE SIN-220Hz-0.3V | -63.13 dB | ≤ -20 | PASS |
-| crunch_drive | total_harmonics_2_9_db | DRIVE SIN-220Hz-0.3V | 0.03227 dB | ≤ 1.5 | PASS |
+| crunch_drive | newton_max_iterations | CRUNCH DI-GTR RR | 8 | ≤ 32 | PASS |
+| crunch_drive | total_esr_db | DRIVE SIN-220Hz-0.3V | -63.12 dB | ≤ -20 | PASS |
+| crunch_drive | total_harmonics_2_9_db | DRIVE SIN-220Hz-0.3V | 0.03219 dB | ≤ 1.5 | PASS |
 | crunch_drive | newton_failures | DRIVE SIN-220Hz-0.3V | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE SIN-220Hz-0.3V | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE SIN-220Hz-0.3V | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | DRIVE SIN-220Hz-0.3V | 6 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE DI-GTR L | -59.39 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | DRIVE DI-GTR L | -59.48 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | DRIVE DI-GTR L | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE DI-GTR L | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE DI-GTR L | 2 | ≤ 3 | PASS |
 | crunch_drive | newton_max_iterations | DRIVE DI-GTR L | 9 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE DI-GTR LL | -60.32 dB | ≤ -20 | PASS |
+| crunch_drive | total_esr_db | DRIVE DI-GTR LL | -60.63 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | DRIVE DI-GTR LL | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE DI-GTR LL | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE DI-GTR LL | 2 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | DRIVE DI-GTR LL | 10 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE DI-GTR R | -60.22 dB | ≤ -20 | PASS |
+| crunch_drive | newton_max_iterations | DRIVE DI-GTR LL | 9 | ≤ 32 | PASS |
+| crunch_drive | total_esr_db | DRIVE DI-GTR R | -60.43 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | DRIVE DI-GTR R | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE DI-GTR R | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE DI-GTR R | 2 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | DRIVE DI-GTR R | 9 | ≤ 32 | PASS |
-| crunch_drive | total_esr_db | DRIVE DI-GTR RR | -59.42 dB | ≤ -20 | PASS |
+| crunch_drive | newton_max_iterations | DRIVE DI-GTR R | 10 | ≤ 32 | PASS |
+| crunch_drive | total_esr_db | DRIVE DI-GTR RR | -59.46 dB | ≤ -20 | PASS |
 | crunch_drive | newton_failures | DRIVE DI-GTR RR | 0 | ≤ 0 | PASS |
 | crunch_drive | newton_unrescued | DRIVE DI-GTR RR | 0 | — | INFO |
 | crunch_drive | newton_median_iterations | DRIVE DI-GTR RR | 2 | ≤ 3 | PASS |
-| crunch_drive | newton_max_iterations | DRIVE DI-GTR RR | 8 | ≤ 32 | PASS |
+| crunch_drive | newton_max_iterations | DRIVE DI-GTR RR | 9 | ≤ 32 | PASS |
 
 ## DC operating point
 
@@ -167,30 +167,30 @@ PASS 107 · FAIL 0
 
 | f | SPICE closed | engine closed | SPICE open | engine open | NFB SPICE | NFB engine |
 |---|---|---|---|---|---|---|
-| 100 Hz | 45.92 | 45.92 | 56.34 | 56.34 | 10.42 | 10.42 |
-| 1000 Hz | 53.54 | 53.54 | 57.85 | 57.86 | 4.32 | 4.32 |
-| 5000 Hz | 69.86 | 69.88 | 77.77 | 77.83 | 7.91 | 7.95 |
+| 100 Hz | 45.93 | 45.93 | 56.34 | 56.34 | 10.42 | 10.42 |
+| 1000 Hz | 53.54 | 53.55 | 57.86 | 57.86 | 4.32 | 4.32 |
+| 5000 Hz | 69.59 | 69.61 | 77.50 | 77.56 | 7.91 | 7.95 |
 
 ## Signals
 
 | Preset | Signal | ESR | best lag | harm. 2–9 | THD F / E | Power F / E | min v(ct) F / E |
 |---|---|---|---|---|---|---|---|
-| CLEAN | SIN-1000Hz-0.025V | -59.7 dB | 0 | 0.02 dB | 7.37 / 7.37 % | 81.1 / 81.2 W | — |
-| OVERDRIVE | SIN-220Hz-0.3V | -67.5 dB | 0 | 0.01 dB | 19.61 / 19.61 % | 32.2 / 32.2 W | 474.38 / 474.37 V |
-| CRUNCH | SIN-220Hz-0.3V | -69.7 dB | 0 | 0.01 dB | 12.00 / 12.00 % | 31.6 / 31.6 W | — |
-| CRUNCH | DI-GTR L | -59.6 dB | 0 | — | — | — | — |
-| CRUNCH | DI-GTR LL | -59.8 dB | 0 | — | — | — | — |
-| CRUNCH | DI-GTR R | -60.8 dB | 0 | — | — | — | — |
-| CRUNCH | DI-GTR RR | -59.4 dB | 0 | — | — | — | — |
-| DRIVE | SIN-220Hz-0.3V | -63.1 dB | 0 | 0.03 dB | 22.53 / 22.53 % | 34.5 / 34.5 W | — |
-| DRIVE | DI-GTR L | -59.4 dB | 0 | — | — | — | — |
-| DRIVE | DI-GTR LL | -60.3 dB | 0 | — | — | — | — |
-| DRIVE | DI-GTR R | -60.2 dB | 0 | — | — | — | — |
-| DRIVE | DI-GTR RR | -59.4 dB | 0 | — | — | — | — |
+| CLEAN | SIN-1000Hz-0.025V | -59.6 dB | 0 | 0.02 dB | 7.37 / 7.37 % | 81.1 / 81.2 W | — |
+| OVERDRIVE | SIN-220Hz-0.3V | -67.5 dB | 0 | 0.01 dB | 19.62 / 19.62 % | 32.2 / 32.2 W | 474.38 / 474.37 V |
+| CRUNCH | SIN-220Hz-0.3V | -69.7 dB | 0 | 0.01 dB | 12.01 / 12.01 % | 31.6 / 31.6 W | — |
+| CRUNCH | DI-GTR L | -59.7 dB | 0 | — | — | — | — |
+| CRUNCH | DI-GTR LL | -60.1 dB | 0 | — | — | — | — |
+| CRUNCH | DI-GTR R | -60.7 dB | 0 | — | — | — | — |
+| CRUNCH | DI-GTR RR | -59.5 dB | 0 | — | — | — | — |
+| DRIVE | SIN-220Hz-0.3V | -63.1 dB | 0 | 0.03 dB | 22.53 / 22.54 % | 34.5 / 34.6 W | — |
+| DRIVE | DI-GTR L | -59.5 dB | 0 | — | — | — | — |
+| DRIVE | DI-GTR LL | -60.6 dB | 0 | — | — | — | — |
+| DRIVE | DI-GTR R | -60.4 dB | 0 | — | — | — | — |
+| DRIVE | DI-GTR RR | -59.5 dB | 0 | — | — | — | — |
 
 ## Stability
 
-60 s silence at Preamp / Master / Presence 1.0: max |out| 4.85e-05 V, RMS first / last 10 s 4.24e-05 / 4.24e-05 V.
+60 s silence at Preamp / Master / Presence 1.0: max |out| 4.55e-05 V, RMS first / last 10 s 4.24e-05 / 4.24e-05 V.
 
 ## Delayed-NFB break
 
diff --git a/harness/reports/M6/20261018_full_acceptance_fs384000_j4exact_hot.md b/harness/reports/M6/20261018_full_acceptance_fs384000_j4exact_hot.md
index 69dc4fe..081078d 100644
--- a/harness/reports/M6/20261018_full_acceptance_fs384000_j4exact_hot.md
+++ b/harness/reports/M6/20261018_full_acceptance_fs384000_j4exact_hot.md
@@ -1,7 +1,7 @@
 # M4 acceptance: full amplifier vs the full netlist
 
-- Date: 2026-10-18, engine commit `9a422dd (dirty)`, ngspice 47, fs = 384000 Hz, J4 exact, SPICE reltol 1e-08
-- Netlist sha256 `83f01b6fd8b64a06`, tubes.lib sha256 `c9c9c88346c69010`
+- Date: 2026-10-18, engine commit `d37baf0 (dirty)`, ngspice 47, fs = 384000 Hz, J4 exact, SPICE reltol 1e-08
+- Netlist sha256 `ffd9b2812204248f`, tubes.lib sha256 `c9c9c88346c69010`
 - Engine: `ampwav --block full` (volts at the jack and across the 16 Ω load), the checks of SPEC §7 M4.
 
 ## Summary
@@ -10,29 +10,29 @@ PASS 20 · FAIL 1
 
 | Section | Check | Item | Measured | Tolerance | Status |
 |---|---|---|---|---|---|
-| hot | total_esr_db | HOT SIN-220Hz-0.3V | -54.54 dB | ≤ -20 | PASS |
-| hot | total_harmonics_2_9_db | HOT SIN-220Hz-0.3V | 0.008907 dB | ≤ 1.5 | PASS |
+| hot | total_esr_db | HOT SIN-220Hz-0.3V | -54.53 dB | ≤ -20 | PASS |
+| hot | total_harmonics_2_9_db | HOT SIN-220Hz-0.3V | 0.008763 dB | ≤ 1.5 | PASS |
 | hot | newton_failures | HOT SIN-220Hz-0.3V | 0 | ≤ 0 | PASS |
 | hot | newton_unrescued | HOT SIN-220Hz-0.3V | 0 | — | INFO |
 | hot | newton_median_iterations | HOT SIN-220Hz-0.3V | 2 | ≤ 3 | PASS |
-| hot | newton_max_iterations | HOT SIN-220Hz-0.3V | 7 | ≤ 32 | PASS |
-| hot | total_esr_db | HOT DI-GTR L | -40.32 dB | ≤ -20 | PASS |
+| hot | newton_max_iterations | HOT SIN-220Hz-0.3V | 6 | ≤ 32 | PASS |
+| hot | total_esr_db | HOT DI-GTR L | -40.27 dB | ≤ -20 | PASS |
 | hot | newton_failures | HOT DI-GTR L | 0 | ≤ 0 | PASS |
 | hot | newton_unrescued | HOT DI-GTR L | 0 | — | INFO |
 | hot | newton_median_iterations | HOT DI-GTR L | 2 | ≤ 3 | PASS |
-| hot | newton_max_iterations | HOT DI-GTR L | 12 | ≤ 32 | PASS |
-| hot | total_esr_db | HOT DI-GTR LL | -40.87 dB | ≤ -20 | PASS |
+| hot | newton_max_iterations | HOT DI-GTR L | 15 | ≤ 32 | PASS |
+| hot | total_esr_db | HOT DI-GTR LL | -41 dB | ≤ -20 | PASS |
 | hot | newton_failures | HOT DI-GTR LL | 0 | ≤ 0 | PASS |
 | hot | newton_unrescued | HOT DI-GTR LL | 0 | — | INFO |
 | hot | newton_median_iterations | HOT DI-GTR LL | 2 | ≤ 3 | PASS |
-| hot | newton_max_iterations | HOT DI-GTR LL | 19 | ≤ 32 | PASS |
-| hot | total_esr_db | HOT DI-GTR R | -41.26 dB | ≤ -20 | PASS |
+| hot | newton_max_iterations | HOT DI-GTR LL | 13 | ≤ 32 | PASS |
+| hot | total_esr_db | HOT DI-GTR R | -41.5 dB | ≤ -20 | PASS |
 | hot | newton_failures | HOT DI-GTR R | 0 | ≤ 0 | PASS |
 | hot | newton_unrescued | HOT DI-GTR R | 0 | — | INFO |
 | hot | newton_median_iterations | HOT DI-GTR R | 2 | ≤ 3 | PASS |
-| hot | newton_max_iterations | HOT DI-GTR R | 13 | ≤ 32 | PASS |
-| hot | total_esr_db | HOT DI-GTR RR | -40.91 dB | ≤ -20 | PASS |
-| hot | newton_failures | HOT DI-GTR RR | 2 | ≤ 0 | FAIL |
+| hot | newton_max_iterations | HOT DI-GTR R | 12 | ≤ 32 | PASS |
+| hot | total_esr_db | HOT DI-GTR RR | -40.86 dB | ≤ -20 | PASS |
+| hot | newton_failures | HOT DI-GTR RR | 1 | ≤ 0 | FAIL |
 | hot | newton_unrescued | HOT DI-GTR RR | 0 | — | INFO |
 | hot | newton_median_iterations | HOT DI-GTR RR | 2 | ≤ 3 | PASS |
 | hot | newton_max_iterations | HOT DI-GTR RR | 32 | ≤ 32 | PASS |
@@ -41,10 +41,10 @@ PASS 20 · FAIL 1
 
 | Preset | Signal | ESR | best lag | harm. 2–9 | THD F / E | Power F / E | min v(ct) F / E |
 |---|---|---|---|---|---|---|---|
-| HOT | SIN-220Hz-0.3V | -54.5 dB | 0 | 0.01 dB | 37.87 / 37.87 % | 178.4 / 178.4 W | — |
+| HOT | SIN-220Hz-0.3V | -54.5 dB | 0 | 0.01 dB | 37.86 / 37.86 % | 178.4 / 178.4 W | — |
 | HOT | DI-GTR L | -40.3 dB | 0 | — | — | — | — |
-| HOT | DI-GTR LL | -40.9 dB | 0 | — | — | — | — |
-| HOT | DI-GTR R | -41.3 dB | 0 | — | — | — | — |
+| HOT | DI-GTR LL | -41.0 dB | 0 | — | — | — | — |
+| HOT | DI-GTR R | -41.5 dB | 0 | — | — | — | — |
 | HOT | DI-GTR RR | -40.9 dB | 0 | — | — | — | — |
 
 ## Delayed-NFB break
diff --git a/harness/reports/M6/20261018_plugin_cpu.md b/harness/reports/M6/20261018_plugin_cpu.md
index ddff5ee..e01907b 100644
--- a/harness/reports/M6/20261018_plugin_cpu.md
+++ b/harness/reports/M6/20261018_plugin_cpu.md
@@ -1,39 +1,39 @@
 # M6 plugin CPU under knob automation
 
-- Date 2026-10-18, commit `9a422dd (dirty)`; `amp2203_render plugin` at the plugin defaults (2x, Power Amp Rate Full, exact J4, Newton tol 1e-4 V, half-steps on; D-054 – D-056, D-060), FIR oversampling, 20 s of DI GTR L at 48000 Hz; processBlock time only.
+- Date 2026-10-18, commit `d37baf0 (dirty)`; `amp2203_render plugin` at the plugin defaults (2x, Power Amp Rate Full, exact J4, Newton tol 1e-4 V, half-steps on; D-054 – D-056, D-060), FIR oversampling, 20 s of DI GTR L at 48000 Hz; processBlock time only.
 - Automation between host blocks: lfo = 10 Hz triangle 0 → 10 → 0, jump = 0 ↔ 10 every 50 ms; "all" moves the six knobs together. One render at a time.
 
 | Base | Knob(s) | Modulation | Host block | CPU (% of one core) | Newton failures (rescued) |
 |---|---|---|---|---|---|
-| default | — | static | 512 | 27.4 | 0 (0) |
-| every knob 10 | — | static | 512 | 50.8 | 32 (32) |
-| default | preampVolume | lfo | 512 | 26.3 | 0 (0) |
-| default | preampVolume | jump | 512 | 25.9 | 0 (0) |
+| default | — | static | 512 | 27.1 | 0 (0) |
+| every knob 10 | — | static | 512 | 50.8 | 40 (40) |
+| default | preampVolume | lfo | 512 | 26.2 | 0 (0) |
+| default | preampVolume | jump | 512 | 25.8 | 0 (0) |
 | default | treble | lfo | 512 | 27.6 | 0 (0) |
-| default | treble | jump | 512 | 27.7 | 0 (0) |
-| default | middle | lfo | 512 | 27.4 | 0 (0) |
-| default | middle | jump | 512 | 27.4 | 0 (0) |
-| default | bass | lfo | 512 | 27.3 | 0 (0) |
-| default | bass | jump | 512 | 27.3 | 0 (0) |
-| default | master | lfo | 512 | 31.6 | 2 (2) |
-| default | master | jump | 512 | 31.9 | 2 (2) |
-| default | presence | lfo | 512 | 28.8 | 0 (0) |
-| default | presence | jump | 512 | 28.7 | 0 (0) |
-| default | all | lfo | 512 | 32.5 | 4 (4) |
-| default | all | jump | 512 | 34.7 | 4 (4) |
-| every knob 10 | preampVolume | lfo | 512 | 43.7 | 18 (18) |
-| every knob 10 | preampVolume | jump | 512 | 43.6 | 19 (19) |
-| every knob 10 | treble | lfo | 512 | 48.6 | 27 (27) |
-| every knob 10 | treble | jump | 512 | 47.8 | 32 (32) |
-| every knob 10 | middle | lfo | 512 | 48.6 | 31 (31) |
-| every knob 10 | middle | jump | 512 | 48.9 | 23 (23) |
-| every knob 10 | bass | lfo | 512 | 52.8 | 32 (32) |
-| every knob 10 | bass | jump | 512 | 52.2 | 31 (31) |
-| every knob 10 | master | lfo | 512 | 38.2 | 6 (6) |
-| every knob 10 | master | jump | 512 | 38.5 | 5 (5) |
-| every knob 10 | presence | lfo | 512 | 47.3 | 34 (34) |
-| every knob 10 | presence | jump | 512 | 47.8 | 26 (26) |
-| every knob 10 | all | lfo | 512 | 33.2 | 3 (3) |
-| every knob 10 | all | jump | 512 | 34.7 | 1 (1) |
-| default | all | jump | 64 | 34.3 | 5 (5) |
-| every knob 10 | all | jump | 64 | 34.7 | 4 (4) |
+| default | treble | jump | 512 | 27.3 | 0 (0) |
+| default | middle | lfo | 512 | 27.2 | 0 (0) |
+| default | middle | jump | 512 | 27.2 | 0 (0) |
+| default | bass | lfo | 512 | 27.1 | 0 (0) |
+| default | bass | jump | 512 | 27.2 | 0 (0) |
+| default | master | lfo | 512 | 31.4 | 4 (4) |
+| default | master | jump | 512 | 31.2 | 5 (5) |
+| default | presence | lfo | 512 | 28.4 | 0 (0) |
+| default | presence | jump | 512 | 28.5 | 0 (0) |
+| default | all | lfo | 512 | 32.8 | 0 (0) |
+| default | all | jump | 512 | 34.6 | 2 (2) |
+| every knob 10 | preampVolume | lfo | 512 | 43.4 | 16 (16) |
+| every knob 10 | preampVolume | jump | 512 | 43.0 | 24 (24) |
+| every knob 10 | treble | lfo | 512 | 48.7 | 24 (24) |
+| every knob 10 | treble | jump | 512 | 47.8 | 25 (25) |
+| every knob 10 | middle | lfo | 512 | 48.2 | 28 (28) |
+| every knob 10 | middle | jump | 512 | 48.5 | 24 (24) |
+| every knob 10 | bass | lfo | 512 | 52.4 | 35 (35) |
+| every knob 10 | bass | jump | 512 | 52.0 | 31 (31) |
+| every knob 10 | master | lfo | 512 | 38.3 | 6 (6) |
+| every knob 10 | master | jump | 512 | 38.4 | 8 (8) |
+| every knob 10 | presence | lfo | 512 | 47.4 | 23 (23) |
+| every knob 10 | presence | jump | 512 | 48.3 | 27 (27) |
+| every knob 10 | all | lfo | 512 | 33.1 | 0 (0) |
+| every knob 10 | all | jump | 512 | 34.6 | 4 (4) |
+| default | all | jump | 64 | 34.2 | 7 (7) |
+| every knob 10 | all | jump | 64 | 34.7 | 10 (10) |
diff --git a/harness/reports/M6/20261018_plugin_null_2x_full.md b/harness/reports/M6/20261018_plugin_null_2x_full.md
index 01fc0d2..6a63df8 100644
--- a/harness/reports/M6/20261018_plugin_null_2x_full.md
+++ b/harness/reports/M6/20261018_plugin_null_2x_full.md
@@ -1,6 +1,6 @@
 # M5 wrapper null test: plugin vs ampwav at 96 kHz with the same resampling
 
-- Date: 2026-10-18, commit `9a422dd (dirty)`; host rate 48000 Hz, 2x, Power Amp Rate full, exact J4
+- Date: 2026-10-18, commit `d37baf0 (dirty)`; host rate 48000 Hz, 2x, Power Amp Rate full, exact J4
 - Plugin: `amp2203_render plugin` (the Amp2203Processor offline). Reference: the processor's oversampler up stage, `ampwav --block full --units fs --j4 exact` at 96000 Hz, the down stage. Default knobs and levels.
 - Tolerance (SPEC §7 M5): ESR ≤ -60 dB.
 
@@ -8,55 +8,55 @@ PASS 26 · FAIL 0
 
 | Filter | Signal | Peak out [FS] | ESR | Status | Render log |
 |---|---|---|---|---|---|
-| fir | SIN-100Hz--40dBFS | 0.145 | -138.5 dB | PASS | processBlock 0.043 s for 0.200 s of audio: 21.5 % of one core, real-time factor 4.64
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 3 |
-| fir | SIN-100Hz--20dBFS | 0.869 | -138.5 dB | PASS | processBlock 0.049 s for 0.200 s of audio: 24.6 % of one core, real-time factor 4.06
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 4 |
-| fir | SIN-100Hz--6dBFS | 0.915 | -138.5 dB | PASS | processBlock 0.049 s for 0.200 s of audio: 24.5 % of one core, real-time factor 4.08
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 9 |
-| fir | SIN-1000Hz--40dBFS | 0.374 | -138.5 dB | PASS | processBlock 0.072 s for 0.200 s of audio: 35.9 % of one core, real-time factor 2.78
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 6 |
-| fir | SIN-1000Hz--20dBFS | 0.828 | -138.5 dB | PASS | processBlock 0.071 s for 0.200 s of audio: 35.4 % of one core, real-time factor 2.83
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 9 |
-| fir | SIN-1000Hz--6dBFS | 0.972 | -138.5 dB | PASS | processBlock 0.076 s for 0.200 s of audio: 38.2 % of one core, real-time factor 2.62
+| fir | SIN-100Hz--40dBFS | 0.145 | -138.5 dB | PASS | processBlock 0.046 s for 0.200 s of audio: 23.1 % of one core, real-time factor 4.32
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 2 |
+| fir | SIN-100Hz--20dBFS | 0.870 | -138.5 dB | PASS | processBlock 0.048 s for 0.200 s of audio: 24.0 % of one core, real-time factor 4.18
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 5 |
+| fir | SIN-100Hz--6dBFS | 0.915 | -138.5 dB | PASS | processBlock 0.050 s for 0.200 s of audio: 24.8 % of one core, real-time factor 4.03
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 10 |
+| fir | SIN-1000Hz--40dBFS | 0.383 | -138.5 dB | PASS | processBlock 0.073 s for 0.200 s of audio: 36.6 % of one core, real-time factor 2.73
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 7 |
+| fir | SIN-1000Hz--20dBFS | 0.850 | -138.5 dB | PASS | processBlock 0.072 s for 0.200 s of audio: 35.9 % of one core, real-time factor 2.78
 latency 49 samples, Newton failures 0 (rescued 0), max iterations 12 |
-| fir | SIN-5000Hz--40dBFS | 0.864 | -138.5 dB | PASS | processBlock 0.090 s for 0.200 s of audio: 44.9 % of one core, real-time factor 2.22
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 19 |
-| fir | SIN-5000Hz--20dBFS | 0.889 | -138.5 dB | PASS | processBlock 0.102 s for 0.200 s of audio: 50.9 % of one core, real-time factor 1.96
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 19 |
-| fir | SIN-5000Hz--6dBFS | 0.930 | -138.5 dB | PASS | processBlock 0.235 s for 0.200 s of audio: 117.3 % of one core, real-time factor 0.85
-latency 49 samples, Newton failures 1009 (rescued 68), max iterations 32 |
-| fir | DI-GTR L | 0.977 | -138.5 dB | PASS | processBlock 1.242 s for 5.000 s of audio: 24.8 % of one core, real-time factor 4.03
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 19 |
-| fir | DI-GTR LL | 0.857 | -138.5 dB | PASS | processBlock 1.202 s for 5.000 s of audio: 24.0 % of one core, real-time factor 4.16
+| fir | SIN-1000Hz--6dBFS | 0.918 | -138.5 dB | PASS | processBlock 0.079 s for 0.200 s of audio: 39.3 % of one core, real-time factor 2.55
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 13 |
+| fir | SIN-5000Hz--40dBFS | 0.857 | -138.5 dB | PASS | processBlock 0.089 s for 0.200 s of audio: 44.7 % of one core, real-time factor 2.24
 latency 49 samples, Newton failures 0 (rescued 0), max iterations 17 |
-| fir | DI-GTR R | 0.945 | -138.5 dB | PASS | processBlock 1.215 s for 5.000 s of audio: 24.3 % of one core, real-time factor 4.12
-latency 49 samples, Newton failures 0 (rescued 0), max iterations 20 |
-| fir | DI-GTR RR | 0.979 | -138.5 dB | PASS | processBlock 1.252 s for 5.000 s of audio: 25.0 % of one core, real-time factor 3.99
+| fir | SIN-5000Hz--20dBFS | 0.891 | -138.5 dB | PASS | processBlock 0.102 s for 0.200 s of audio: 50.8 % of one core, real-time factor 1.97
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 19 |
+| fir | SIN-5000Hz--6dBFS | 0.863 | -138.5 dB | PASS | processBlock 0.515 s for 0.200 s of audio: 257.3 % of one core, real-time factor 0.39
+latency 49 samples, Newton failures 3518 (rescued 89), max iterations 32 |
+| fir | DI-GTR L | 0.984 | -138.5 dB | PASS | processBlock 1.236 s for 5.000 s of audio: 24.7 % of one core, real-time factor 4.04
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 18 |
+| fir | DI-GTR LL | 0.861 | -138.5 dB | PASS | processBlock 1.189 s for 5.000 s of audio: 23.8 % of one core, real-time factor 4.21
 latency 49 samples, Newton failures 0 (rescued 0), max iterations 17 |
-| iir | SIN-100Hz--40dBFS | 0.145 | -138.5 dB | PASS | processBlock 0.041 s for 0.200 s of audio: 20.7 % of one core, real-time factor 4.82
+| fir | DI-GTR R | 0.944 | -138.5 dB | PASS | processBlock 1.206 s for 5.000 s of audio: 24.1 % of one core, real-time factor 4.15
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 16 |
+| fir | DI-GTR RR | 0.990 | -138.5 dB | PASS | processBlock 1.245 s for 5.000 s of audio: 24.9 % of one core, real-time factor 4.02
+latency 49 samples, Newton failures 0 (rescued 0), max iterations 19 |
+| iir | SIN-100Hz--40dBFS | 0.145 | -138.5 dB | PASS | processBlock 0.042 s for 0.200 s of audio: 20.8 % of one core, real-time factor 4.81
 latency 4 samples, Newton failures 0 (rescued 0), max iterations 2 |
-| iir | SIN-100Hz--20dBFS | 0.870 | -138.5 dB | PASS | processBlock 0.044 s for 0.200 s of audio: 22.2 % of one core, real-time factor 4.51
-latency 4 samples, Newton failures 0 (rescued 0), max iterations 6 |
-| iir | SIN-100Hz--6dBFS | 0.915 | -138.5 dB | PASS | processBlock 0.046 s for 0.200 s of audio: 22.8 % of one core, real-time factor 4.39
+| iir | SIN-100Hz--20dBFS | 0.870 | -138.5 dB | PASS | processBlock 0.044 s for 0.200 s of audio: 22.1 % of one core, real-time factor 4.52
+latency 4 samples, Newton failures 0 (rescued 0), max iterations 4 |
+| iir | SIN-100Hz--6dBFS | 0.915 | -138.5 dB | PASS | processBlock 0.045 s for 0.200 s of audio: 22.4 % of one core, real-time factor 4.47
 latency 4 samples, Newton failures 0 (rescued 0), max iterations 6 |
-| iir | SIN-1000Hz--40dBFS | 0.414 | -138.5 dB | PASS | processBlock 0.067 s for 0.200 s of audio: 33.4 % of one core, real-time factor 3.00
+| iir | SIN-1000Hz--40dBFS | 0.402 | -138.5 dB | PASS | processBlock 0.066 s for 0.200 s of audio: 32.8 % of one core, real-time factor 3.05
 latency 4 samples, Newton failures 0 (rescued 0), max iterations 7 |
-| iir | SIN-1000Hz--20dBFS | 0.928 | -138.5 dB | PASS | processBlock 0.071 s for 0.200 s of audio: 35.3 % of one core, real-time factor 2.84
-latency 4 samples, Newton failures 0 (rescued 0), max iterations 9 |
-| iir | SIN-1000Hz--6dBFS | 1.044 | -138.5 dB | PASS | processBlock 0.075 s for 0.200 s of audio: 37.4 % of one core, real-time factor 2.67
-latency 4 samples, Newton failures 0 (rescued 0), max iterations 22 |
-| iir | SIN-5000Hz--40dBFS | 0.982 | -138.5 dB | PASS | processBlock 0.090 s for 0.200 s of audio: 44.9 % of one core, real-time factor 2.23
+| iir | SIN-1000Hz--20dBFS | 0.932 | -138.5 dB | PASS | processBlock 0.070 s for 0.200 s of audio: 34.9 % of one core, real-time factor 2.87
+latency 4 samples, Newton failures 0 (rescued 0), max iterations 10 |
+| iir | SIN-1000Hz--6dBFS | 1.087 | -138.5 dB | PASS | processBlock 0.076 s for 0.200 s of audio: 37.8 % of one core, real-time factor 2.65
+latency 4 samples, Newton failures 0 (rescued 0), max iterations 19 |
+| iir | SIN-5000Hz--40dBFS | 0.987 | -138.5 dB | PASS | processBlock 0.090 s for 0.200 s of audio: 45.0 % of one core, real-time factor 2.22
 latency 4 samples, Newton failures 0 (rescued 0), max iterations 16 |
-| iir | SIN-5000Hz--20dBFS | 1.015 | -138.5 dB | PASS | processBlock 0.101 s for 0.200 s of audio: 50.6 % of one core, real-time factor 1.98
-latency 4 samples, Newton failures 0 (rescued 0), max iterations 22 |
-| iir | SIN-5000Hz--6dBFS | 1.020 | -138.5 dB | PASS | processBlock 0.139 s for 0.200 s of audio: 69.3 % of one core, real-time factor 1.44
-latency 4 samples, Newton failures 268 (rescued 184), max iterations 32 |
-| iir | DI-GTR L | 0.985 | -138.5 dB | PASS | processBlock 1.250 s for 5.000 s of audio: 25.0 % of one core, real-time factor 4.00
+| iir | SIN-5000Hz--20dBFS | 1.048 | -138.5 dB | PASS | processBlock 0.100 s for 0.200 s of audio: 50.1 % of one core, real-time factor 1.99
+latency 4 samples, Newton failures 0 (rescued 0), max iterations 18 |
+| iir | SIN-5000Hz--6dBFS | 1.032 | -138.5 dB | PASS | processBlock 0.574 s for 0.200 s of audio: 286.8 % of one core, real-time factor 0.35
+latency 4 samples, Newton failures 3955 (rescued 58), max iterations 32 |
+| iir | DI-GTR L | 0.950 | -138.5 dB | PASS | processBlock 1.230 s for 5.000 s of audio: 24.6 % of one core, real-time factor 4.07
 latency 4 samples, Newton failures 0 (rescued 0), max iterations 18 |
-| iir | DI-GTR LL | 0.985 | -138.5 dB | PASS | processBlock 1.217 s for 5.000 s of audio: 24.3 % of one core, real-time factor 4.11
-latency 4 samples, Newton failures 0 (rescued 0), max iterations 22 |
-| iir | DI-GTR R | 1.027 | -138.5 dB | PASS | processBlock 1.216 s for 5.000 s of audio: 24.3 % of one core, real-time factor 4.11
+| iir | DI-GTR LL | 0.955 | -138.5 dB | PASS | processBlock 1.175 s for 5.000 s of audio: 23.5 % of one core, real-time factor 4.25
+latency 4 samples, Newton failures 0 (rescued 0), max iterations 19 |
+| iir | DI-GTR R | 1.046 | -138.5 dB | PASS | processBlock 1.192 s for 5.000 s of audio: 23.8 % of one core, real-time factor 4.19
 latency 4 samples, Newton failures 0 (rescued 0), max iterations 18 |
-| iir | DI-GTR RR | 1.036 | -138.5 dB | PASS | processBlock 1.250 s for 5.000 s of audio: 25.0 % of one core, real-time factor 4.00
-latency 4 samples, Newton failures 0 (rescued 0), max iterations 21 |
+| iir | DI-GTR RR | 1.049 | -138.5 dB | PASS | processBlock 1.230 s for 5.000 s of audio: 24.6 % of one core, real-time factor 4.07
+latency 4 samples, Newton failures 0 (rescued 0), max iterations 23 |
diff --git a/harness/reports/M6/20261018_pluginval_au.log b/harness/reports/M6/20261018_pluginval_au.log
index 277776b..ff74411 100644
--- a/harness/reports/M6/20261018_pluginval_au.log
+++ b/harness/reports/M6/20261018_pluginval_au.log
@@ -1,5 +1,5 @@
 Started validating: /Users/kimmo/Library/Audio/Plug-Ins/Components/Amp2203.component
-Random seed: 0xe186bf
+Random seed: 0x2e108e
 Validation started
 Strictness level: 5
 -----------------------------------------------------------------
diff --git a/harness/reports/M6/20261018_pluginval_vst3.log b/harness/reports/M6/20261018_pluginval_vst3.log
index 7f785b4..619f549 100644
--- a/harness/reports/M6/20261018_pluginval_vst3.log
+++ b/harness/reports/M6/20261018_pluginval_vst3.log
@@ -1,5 +1,5 @@
 Started validating: /Users/kimmo/Library/Audio/Plug-Ins/VST3/Amp2203.vst3
-Random seed: 0x39def85
+Random seed: 0x1ec231b
 Validation started
 Strictness level: 5
 -----------------------------------------------------------------
diff --git a/harness/reports/M6/20261018_x2_rates_d062_full2x.md b/harness/reports/M6/20261018_x2_rates_d062_full2x.md
new file mode 100644
index 0000000..f226790
--- /dev/null
+++ b/harness/reports/M6/20261018_x2_rates_d062_full2x.md
@@ -0,0 +1,48 @@
+# M6 A1: full engine (exact J4) at lower internal rates, plugin model check
+
+- Date 2026-10-18; options: tol 0.0001; rates 48 kHz × [2].
+- Plugin model check (D-051): ESR ≤ -20 dB vs SPICE (cached 384000 Hz references, 48 kHz band, first 5 s of every DI track, first 0.1 s excluded). Unseen settings: the 16 X4 validation settings, 10 s, vs the engine at 16x (first 1 s excluded). Cost: ampwav --stats on 10 s of DI GTR L, one run at a time; oversampling filters not included.
+
+## Summary
+
+| Rate | vs SPICE worst (CRUNCH / DRIVE / HOT) | Check | Unseen settings vs 16x (worst / median) | Newton failures (not rescued) / runs, max iterations | Cost default / HOT (% of one core) |
+|---|---|---|---|---|---|
+| 2x (96 kHz) | -45.3 / -48.5 / -24.0 dB | PASS | -20.8 / -39.0 dB | 102 (3) / 28, 32 | 27.1 / 42.2 |
+
+## vs SPICE per clip
+
+| Clip | 2x |
+|---|---|
+| CRUNCH GTR L | -45.8 dB |
+| CRUNCH GTR LL | -45.3 dB |
+| CRUNCH GTR R | -46.1 dB |
+| CRUNCH GTR RR | -45.7 dB |
+| DRIVE GTR L | -48.5 dB |
+| DRIVE GTR LL | -49.7 dB |
+| DRIVE GTR R | -49.5 dB |
+| DRIVE GTR RR | -48.9 dB |
+| HOT GTR L | -24.3 dB |
+| HOT GTR LL | -25.2 dB |
+| HOT GTR R | -25.2 dB |
+| HOT GTR RR | -24.0 dB |
+
+## Aliasing (power outside the harmonics of f0, relative to the total; 16x for reference)
+
+Each cell: non-harmonic power, then Newton failures (not rescued) in that 2 s run. Non-converged samples add non-harmonic power, so a cell with many failures measures solver error as well as aliasing.
+
+| Preset | f0 | amplitude (FS) | 16x | 2x |
+|---|---|---|---|---|
+| CRUNCH | 5000 Hz | 0.1 | -25.3 dB, 0 (0) | -20.5 dB, 0 (0) |
+| CRUNCH | 5000 Hz | 0.4 | -24.4 dB, 0 (0) | -17.4 dB, 4705 (3589) |
+| CRUNCH | 9000 Hz | 0.1 | -40.9 dB, 0 (0) | -18.2 dB, 0 (0) |
+| CRUNCH | 9000 Hz | 0.4 | -40.0 dB, 0 (0) | -14.9 dB, 5374 (147) |
+| HOT | 5000 Hz | 0.1 | -25.1 dB, 0 (0) | -16.5 dB, 369 (0) |
+| HOT | 5000 Hz | 0.4 | -25.0 dB, 0 (0) | -12.1 dB, 10446 (8982) |
+| HOT | 9000 Hz | 0.1 | -38.8 dB, 20 (0) | -16.4 dB, 915 (0) |
+| HOT | 9000 Hz | 0.4 | -33.3 dB, 42 (0) | -15.0 dB, 4243 (18) |
+
+## Cost
+
+| Rate | ns per engine sample (default / HOT) | % of one core at 48 kHz |
+|---|---|---|
+| 2x | 2820 / 4400 | 27.1 / 42.2 |
diff --git a/harness/testbench_gen.py b/harness/testbench_gen.py
index 1611397..2fc84bc 100644
--- a/harness/testbench_gen.py
+++ b/harness/testbench_gen.py
@@ -28,7 +28,7 @@
 
 # Partition of the reference netlist (SPEC §4.2). Every element belongs to exactly one block.
 PARTITION = {
-    'B12': 'Vin R2 R3 X1a R1 C1 R4 C3 R5 C4 C5 RVR1a RVR1b X1b R6 R7',   # V1a + V1b, joint root (D-017)
+    'B12': 'Vin R2 R3 X1a R1 C1 C2 R4 C3 R5 C4 C5 RVR1a RVR1b X1b R6 R7',   # V1a + V1b, joint root (D-017); C2 D-062
     'B3': 'C7 R10 C8 R11 X2a R9 R12 X2b R13',
     'B4': 'C10 R15 C11 C12 RVR3a RVR3b RVR5 RVR4a RVR4b RVR2a RVR2b',
     'B5': 'C9 R17 R16 R19 C15 R20 R23 C17 RVR6 R22 X3a X3b R18 R21',
diff --git a/harness/testbenches/b12.cir b/harness/testbenches/b12.cir
index fb30271..9bb46fe 100644
--- a/harness/testbenches/b12.cir
+++ b/harness/testbenches/b12.cir
@@ -1,5 +1,5 @@
 * harness testbench "b12" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * B12 StageV1aV1b (V1a and V1b, joint root). Input: guitar source at node in.
 * Output: p1b (open). Supply bpA: constant from F op.
 .include tubes.lib
@@ -16,6 +16,7 @@ R3 in g1a 68k
 X1a p1a g1a k1a 12AX7
 R1 k1a 0 2.7k
 C1 k1a 0 0.68u
+C2 p1a k1a 100p
 R4 bpA p1a 100k
 C3 p1a nA 0.022u
 R5 nA vtop 470k
diff --git a/harness/testbenches/b123.cir b/harness/testbenches/b123.cir
index a8d8721..19d8b82 100644
--- a/harness/testbenches/b123.cir
+++ b/harness/testbenches/b123.cir
@@ -1,5 +1,5 @@
 * harness testbench "b123" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * Junction reference for J2: B12 and B3 joined directly (no J-Thevenin source), for the SPICE
 * partition-error study of J2 (harness/partition.py). Input: guitar source at node in.
 * Output: k2b (open). Supplies bpA, bpX: constant from F op.
@@ -17,6 +17,7 @@ R3 in g1a 68k
 X1a p1a g1a k1a 12AX7
 R1 k1a 0 2.7k
 C1 k1a 0 0.68u
+C2 p1a k1a 100p
 R4 bpA p1a 100k
 C3 p1a nA 0.022u
 R5 nA vtop 470k
diff --git a/harness/testbenches/b1234.cir b/harness/testbenches/b1234.cir
index 34f2361..ff9d135 100644
--- a/harness/testbenches/b1234.cir
+++ b/harness/testbenches/b1234.cir
@@ -1,5 +1,5 @@
 * harness testbench "b1234" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * B1234 Preamp: B12, B3 and B4 in one tree with an 8-port root (no J2 / J3; DECISIONS D-038).
 * Input: guitar source at node in. Output: y (open, master wiper). Supplies bpA, bpX: constant
 * from F op (the cascade study drives them with F's recorded waveforms).
@@ -17,6 +17,7 @@ R3 in g1a 68k
 X1a p1a g1a k1a 12AX7
 R1 k1a 0 2.7k
 C1 k1a 0 0.68u
+C2 p1a k1a 100p
 R4 bpA p1a 100k
 C3 p1a nA 0.022u
 R5 nA vtop 470k
diff --git a/harness/testbenches/b3.cir b/harness/testbenches/b3.cir
index 1041315..14635e3 100644
--- a/harness/testbenches/b3.cir
+++ b/harness/testbenches/b3.cir
@@ -1,5 +1,5 @@
 * harness testbench "b3" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * B3 StageV2aV2b. Input: J2 Thevenin source (v_oc(p1b), R_th2) into node p1b.
 * Output: k2b (open). Supply bpX: constant from F op.
 .include tubes.lib
diff --git a/harness/testbenches/b34.cir b/harness/testbenches/b34.cir
index 09bb7f3..306ce45 100644
--- a/harness/testbenches/b34.cir
+++ b/harness/testbenches/b34.cir
@@ -1,5 +1,5 @@
 * harness testbench "b34" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * B34 StageV2aV2bToneStack: B3 and B4 joined in one tree (no J3; DECISIONS D-033).
 * Input: J2 Thevenin source (v_oc(p1b), R_th2) into node p1b. Output: y (open, master wiper).
 * Supply bpX: constant from F op.
diff --git a/harness/testbenches/b4.cir b/harness/testbenches/b4.cir
index c381998..c5c988b 100644
--- a/harness/testbenches/b4.cir
+++ b/harness/testbenches/b4.cir
@@ -1,5 +1,5 @@
 * harness testbench "b4" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * B4 ToneStackMaster. Input: J3 Thevenin source (v_oc(k2b), R_th3) into node k2b.
 * Output: y (open, master wiper).
 .include tubes.lib
diff --git a/harness/testbenches/b56.cir b/harness/testbenches/b56.cir
index a30b8bb..7f48cf1 100644
--- a/harness/testbenches/b56.cir
+++ b/harness/testbenches/b56.cir
@@ -1,5 +1,5 @@
 * harness testbench "b56" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * B56+B7: phase inverter, power stage and supply with instantaneous NFB (VERIFICATION §1).
 * Input: J4 Thevenin source (v_oc(y), R_th4) into node y; R_th4 = DC formula (WDF_DESIGN §6).
 * Preamp loads on bpA / bpX: constant current sinks from F op (recorded waveforms in M4).
diff --git a/harness/testbenches/b56j5.cir b/harness/testbenches/b56j5.cir
index 4fade9a..c37cd5e 100644
--- a/harness/testbenches/b56j5.cir
+++ b/harness/testbenches/b56j5.cir
@@ -1,5 +1,5 @@
 * harness testbench "b56j5" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * J5 partition reference: B56+B7 as b56 (closed loop, instantaneous NFB), but C14 / C16 are fed
 * by J5 Thevenin sources (VCVS copies of the unloaded PI plates p3a / p3b behind R_thA / R_thB)
 * instead of the plates themselves (harness/partition_j5.py).
diff --git a/harness/testbenches/b5open.cir b/harness/testbenches/b5open.cir
index c8791ee..48b6eb4 100644
--- a/harness/testbenches/b5open.cir
+++ b/harness/testbenches/b5open.cir
@@ -1,5 +1,5 @@
 * harness testbench "b5open" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * B5-open: phase inverter with R22 driven by the recorded speaker voltage (ideal source).
 * Input: J4 Thevenin source into node y. Outputs: p3a, p3b (open).
 * Recorded sources (from a B56 run): out, bpX. DC values from F op.
diff --git a/harness/testbenches/b6.cir b/harness/testbenches/b6.cir
index 9aaefbe..9559eb0 100644
--- a/harness/testbenches/b6.cir
+++ b/harness/testbenches/b6.cir
@@ -1,5 +1,5 @@
 * harness testbench "b6" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * B6 PowerStage driven by the recorded PI open-circuit outputs through R_thA / R_thB.
 * No Vin: both inputs are recorded sources (from a B56 / B5-open run). Output: out.
 * Recorded supply rails (from a B56 run): ct, nScr. DC values from F op.
diff --git a/harness/testbenches/full.cir b/harness/testbenches/full.cir
index 9b3ceb9..57cc396 100644
--- a/harness/testbenches/full.cir
+++ b/harness/testbenches/full.cir
@@ -1,5 +1,5 @@
 * harness testbench "full" -- GENERATED by harness/testbench_gen.py, do not edit
-* source: reference/spice/jcm800_2203.cir (sha256 83f01b6fd8b64a06)
+* source: reference/spice/jcm800_2203.cir (sha256 ffd9b2812204248f)
 * Reference F: identical to the reference netlist.
 * Input: Vin in 0 (replaced by a filesource for transient runs).
 * Reference model. Knob params are rotations 0..1. See ASSUMPTIONS in README.
@@ -18,6 +18,7 @@ R3 in g1a 68k
 X1a p1a g1a k1a 12AX7
 R1 k1a 0 2.7k
 C1 k1a 0 0.68u
+C2 p1a k1a 100p
 R4 bpA p1a 100k
 C3 p1a nA 0.022u
 
diff --git a/reference/spice/jcm800_2203.cir b/reference/spice/jcm800_2203.cir
index b743393..813f89e 100644
--- a/reference/spice/jcm800_2203.cir
+++ b/reference/spice/jcm800_2203.cir
@@ -15,6 +15,7 @@ R3 in g1a 68k
 X1a p1a g1a k1a 12AX7
 R1 k1a 0 2.7k
 C1 k1a 0 0.68u
+C2 p1a k1a 100p
 R4 bpA p1a 100k
 C3 p1a nA 0.022u
 
diff --git a/tests/test_phase_inverter.cpp b/tests/test_phase_inverter.cpp
index 534146e..2952f23 100644
--- a/tests/test_phase_inverter.cpp
+++ b/tests/test_phase_inverter.cpp
@@ -41,10 +41,10 @@ TEST_CASE("PhaseInverter starts at the DC operating point", "[stage5][m4]") {
     setup(s);
     // full-netlist op (ngspice 47), DC tolerance 0.5 % (VERIFICATION §7); the engine is ≈ 1 mV off at
     // the tail because tubes.lib's 1 GΩ plate–cathode resistors are omitted (WDF_DESIGN §3.1)
-    const std::pair<const char*, double> ref[] = {{"g3a", 43.52260078966601}, {"nf", 43.521599385375474},
-                                                  {"k3", 44.93336791716606},  {"g3b", 43.522600789666015},
-                                                  {"ng", 13.483951021319733}, {"p3a", 270.8809249953309},
-                                                  {"p3b", 262.2705821268219}};
+    const std::pair<const char*, double> ref[] = {{"g3a", 43.8294735664613}, {"nf", 43.82847215398154},
+                                                  {"k3", 45.25019513654581},  {"g3b", 43.82947356646135},
+                                                  {"ng", 13.57902696479027}, {"p3a", 272.6112625373205},
+                                                  {"p3b", 263.9511986968434}};
     for (const auto& [n, v] : ref) {
         INFO(n << ": " << probe(s, n) << " (SPICE " << v << ")");
         REQUIRE(std::fabs(probe(s, n) / v - 1.0) < 5e-3);
diff --git a/tests/test_preamp.cpp b/tests/test_preamp.cpp
index 6f8ca27..3230463 100644
--- a/tests/test_preamp.cpp
+++ b/tests/test_preamp.cpp
@@ -31,8 +31,8 @@ TEST_CASE("Preamp starts at the DC operating point", "[preamp][m3]") {
     s.prepare(kFs, 20.0);
     s.reset(0.0);
     // CIRCUIT.md §5 (F operating point); the harness checks every node against the testbench op
-    for (const auto& [node, v] : {std::pair{"p1a", 296.402}, {"k1a", 2.510}, {"p1b", 352.433}, {"p2a", 231.130},
-                                  {"k2a", 1.404}, {"k2b", 231.686}}) {
+    for (const auto& [node, v] : {std::pair{"p1a", 298.325995}, {"k1a", 2.527076}, {"p1b", 354.750235}, {"p2a", 232.577102},
+                                  {"k2a", 1.413853}, {"k2b", 233.140404}}) {
         INFO(node);
         REQUIRE(std::fabs(probe(s, node) / v - 1.0) < 5e-3);
     }
@@ -102,7 +102,7 @@ TEST_CASE("Preamp follows its supply inputs and stays finite far beyond the sign
     s.setSupplyVoltages(380.0, 395.0);
     s.reset(0.0);
     REQUIRE(probe(s, "bpa") == 380.0);
-    REQUIRE(probe(s, "p1b") < 352.433);  // lower supply, lower plate voltage
+    REQUIRE(probe(s, "p1b") < 354.750235);  // lower supply, lower plate voltage
     for (long k = 0; k < static_cast<long>(0.05 * kFs); ++k)
         REQUIRE(std::isfinite(s.process(sine(k, 220.0, 20.0))));  // 10× the overdrive level
     REQUIRE(s.sanitizeEvents() == 0);
diff --git a/tests/test_stage12.cpp b/tests/test_stage12.cpp
index 23e8564..8272480 100644
--- a/tests/test_stage12.cpp
+++ b/tests/test_stage12.cpp
@@ -29,9 +29,9 @@ TEST_CASE("StageV1aV1b starts at the DC operating point", "[stage12][m2]") {
     s.prepare(kFs, 20.0);
     s.reset(0.0);
     // CIRCUIT.md §5 (F operating point); the harness checks every node against the testbench op
-    REQUIRE(std::fabs(probe(s, "p1a") / 296.402 - 1.0) < 5e-3);
-    REQUIRE(std::fabs(probe(s, "k1a") / 2.510 - 1.0) < 5e-3);
-    REQUIRE(std::fabs(probe(s, "p1b") / 352.433 - 1.0) < 5e-3);
+    REQUIRE(std::fabs(probe(s, "p1a") / 298.325995 - 1.0) < 5e-3);
+    REQUIRE(std::fabs(probe(s, "k1a") / 2.527076 - 1.0) < 5e-3);
+    REQUIRE(std::fabs(probe(s, "p1b") / 354.750235 - 1.0) < 5e-3);
 
     const double p1b = probe(s, "p1b");
     for (int n = 0; n < 4096; ++n) {
@@ -40,8 +40,8 @@ TEST_CASE("StageV1aV1b starts at the DC operating point", "[stage12][m2]") {
     }
     REQUIRE(s.newtonStats().failures == 0);
     REQUIRE(s.newtonStats().maxIterations == 0);  // the warm start is the solution
-    REQUIRE(std::fabs(s.supplyCurrent() - ((389.349603 - probe(s, "p1a")) / 100e3 +
-                                           (389.349603 - p1b) / 100e3)) < 1e-15);
+    REQUIRE(std::fabs(s.supplyCurrent() - ((391.921506 - probe(s, "p1a")) / 100e3 +
+                                           (391.921506 - p1b) / 100e3)) < 1e-15);
 }
 
 TEST_CASE("StageV1aV1b Preamp Volume jump stays finite and rate-limits matrix updates", "[stage12][m2]") {
diff --git a/tests/test_stage3.cpp b/tests/test_stage3.cpp
index 38420eb..7d258e5 100644
--- a/tests/test_stage3.cpp
+++ b/tests/test_stage3.cpp
@@ -30,9 +30,9 @@ TEST_CASE("StageV2aV2b starts at the DC operating point", "[stage3][m3]") {
     s.prepare(kFs);
     s.reset(kVp1b);
     // CIRCUIT.md §5 (F operating point); the harness checks every node against the testbench op
-    REQUIRE(std::fabs(probe(s, "p2a") / 231.130 - 1.0) < 5e-3);
-    REQUIRE(std::fabs(probe(s, "k2a") / 1.404 - 1.0) < 5e-3);
-    REQUIRE(std::fabs(probe(s, "k2b") / 231.686 - 1.0) < 5e-3);
+    REQUIRE(std::fabs(probe(s, "p2a") / 232.577102 - 1.0) < 5e-3);
+    REQUIRE(std::fabs(probe(s, "k2a") / 1.413853 - 1.0) < 5e-3);
+    REQUIRE(std::fabs(probe(s, "k2b") / 233.140404 - 1.0) < 5e-3);
 
     const double k2b = probe(s, "k2b");
     for (int n = 0; n < 4096; ++n)
@@ -43,7 +43,7 @@ TEST_CASE("StageV2aV2b starts at the DC operating point", "[stage3][m3]") {
 
 TEST_CASE("StageV2aV2b DC satisfies KCL with the supply on V2b's plate", "[stage3][m3]") {
     // checks the exact supply offsets: V2b's plate port ends on bpX, which is not a network node
-    for (double vbpX : {402.335999, 350.0, 450.0}) {
+    for (double vbpX : {404.998185, 350.0, 450.0}) {
         StageV2aV2b s;
         s.prepare(kFs);
         s.setSupplyVoltage(vbpX);
diff --git a/tests/test_stage34.cpp b/tests/test_stage34.cpp
index 9ca45b1..8d0719c 100644
--- a/tests/test_stage34.cpp
+++ b/tests/test_stage34.cpp
@@ -31,9 +31,9 @@ TEST_CASE("StageV2aV2bToneStack starts at the DC operating point", "[stage34][m3
     StageV2aV2bToneStack s;
     s.prepare(kFs, 20.0);
     s.reset(kVp1b);
-    REQUIRE(std::fabs(probe(s, "p2a") / 231.130 - 1.0) < 5e-3);  // CIRCUIT.md §5
-    REQUIRE(std::fabs(probe(s, "k2b") / 231.686 - 1.0) < 5e-3);
-    REQUIRE(std::fabs(probe(s, "nd") / 231.686 - 1.0) < 5e-3);   // R15 carries no DC current
+    REQUIRE(std::fabs(probe(s, "p2a") / 232.577102 - 1.0) < 5e-3);  // CIRCUIT.md §5
+    REQUIRE(std::fabs(probe(s, "k2b") / 233.140404 - 1.0) < 5e-3);
+    REQUIRE(std::fabs(probe(s, "nd") / 233.140404 - 1.0) < 5e-3);   // R15 carries no DC current
     REQUIRE(std::fabs(probe(s, "y")) < 1e-9);                    // the tone stack is AC-coupled
     for (int n = 0; n < 4096; ++n)
         REQUIRE(std::fabs(s.process(kVp1b)) < 1e-9);  // silence in, silence out (SPEC §3.6)