diff --git a/player-asbuilt.html b/player-asbuilt.html
index ac4fd68..6a3840a 100644
--- a/player-asbuilt.html
+++ b/player-asbuilt.html
@@ -18,8 +18,10 @@
       never hides the readout) with arcade pushbuttons spread below — PREV far
       left, NEXT far right, a big central PLAY — so you don't hit the wrong one;
     • rear I/O: external trigger in (footswitch), a 1/4" instrument pass-through
-      with the click injected, and a shared 1/4" balanced-TRS main out; plus a
-      MAX98357A-style monitor speaker, USB-C and a PWR LED, in a compact matte case.
+      with the click mixed in the ANALOG domain (DAC → summing op-amp → balanced
+      line driver), a shared 1/4" balanced-TRS main out, plus an analog monitor
+      amp + speaker, USB-C and a PWR LED, in a compact matte case.
+  A rough bill of materials for all of this is shown below the loader on the page.
   Compare with the idealized /player.html. One file, no deps; shares src/engine.js.
 -->
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@@ -151,6 +153,17 @@
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+
+  /* ---- bill of materials ---- */
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@@ -221,6 +234,44 @@
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+<!-- ===================== BILL OF MATERIALS ===================== -->
+<div class="panel">
+  <h2>Bill of materials</h2>
+  <p class="sub">Rough parts list for the device above — an RP2040 build with analog click injection.
+    Ballpark one-off prices (USD); cheaper at volume.</p>
+  <table class="bom">
+    <thead><tr><th>Part</th><th class="q">Qty</th><th class="c">~$</th></tr></thead>
+    <tbody>
+      <tr class="grp"><td colspan="3">Brain &amp; display</td></tr>
+      <tr><td class="part">RP2040 board, USB‑C <span class="spec">— e.g. Waveshare RP2040‑Zero / Pico‑clone</span></td><td class="q">1</td><td class="c">4</td></tr>
+      <tr><td class="part">2.0″ 320×240 IPS TFT, ST7789 <span class="spec">— SPI</span></td><td class="q">1</td><td class="c">8</td></tr>
+      <tr class="grp"><td colspan="3">Beat bar</td></tr>
+      <tr><td class="part">WS2812B / SK6812 RGB LED <span class="spec">— 4×16 matrix (or 4× 16‑px strips), PIO‑driven</span></td><td class="q">64</td><td class="c">6</td></tr>
+      <tr class="grp"><td colspan="3">Controls</td></tr>
+      <tr><td class="part">Arcade pushbutton, 24 mm <span class="spec">— Prev · Next · Tap</span></td><td class="q">3</td><td class="c">4</td></tr>
+      <tr><td class="part">Arcade pushbutton, 30 mm <span class="spec">— Play</span></td><td class="q">1</td><td class="c">2</td></tr>
+      <tr><td class="part">EC11 rotary encoder + knurled knob <span class="spec">— tempo</span></td><td class="q">1</td><td class="c">2</td></tr>
+      <tr class="grp"><td colspan="3">Audio — analog click injection</td></tr>
+      <tr><td class="part">PCM5102A I²S DAC <span class="spec">— line‑level click</span></td><td class="q">1</td><td class="c">3</td></tr>
+      <tr><td class="part">Dual op‑amp, NE5532 / OPA2134 <span class="spec">— hi‑Z instrument buffer + summing mixer</span></td><td class="q">1</td><td class="c">1</td></tr>
+      <tr><td class="part">Balanced line driver, DRV134 <span class="spec">— (or cross‑coupled op‑amp) → 1/4″ TRS out</span></td><td class="q">1</td><td class="c">4</td></tr>
+      <tr><td class="part">PAM8302A mono Class‑D + 8 Ω 2 W speaker <span class="spec">— monitor</span></td><td class="q">1</td><td class="c">4</td></tr>
+      <tr class="grp"><td colspan="3">Connectors &amp; power</td></tr>
+      <tr><td class="part">1/4″ jack <span class="spec">— Inst In (TS) · Out (TRS) · Trig In (TS)</span></td><td class="q">3</td><td class="c">3</td></tr>
+      <tr><td class="part">LiPo 1200 mAh + TP4056 charger + 5 V boost</td><td class="q">1</td><td class="c">6</td></tr>
+      <tr><td class="part">Power slide switch + PWR LED</td><td class="q">1</td><td class="c">1</td></tr>
+      <tr class="grp"><td colspan="3">Build</td></tr>
+      <tr><td class="part">Custom PCB (or perfboard)</td><td class="q">1</td><td class="c">5</td></tr>
+      <tr><td class="part">Passives, headers, wire <span class="spec">— R/C for the analog stage + decoupling</span></td><td class="q">—</td><td class="c">3</td></tr>
+      <tr><td class="part">3D‑printed enclosure + screws / standoffs</td><td class="q">1</td><td class="c">5</td></tr>
+      <tr class="total"><td>Total (one‑off)</td><td class="q"></td><td class="c">≈ $61</td></tr>
+    </tbody>
+  </table>
+  <p class="sub" style="margin-top:12px">Audio is summed in the <b>analog domain</b>: the DAC's click is mixed with a high‑impedance
+    buffer of the 1/4″ instrument input, then fed to the balanced line driver (1/4″ TRS out) and the monitor amp —
+    so your instrument is never re‑digitised (no added latency).</p>
+</div>
+
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