diff --git a/app/static/js/services/soundfontPlayer.js b/app/static/js/services/soundfontPlayer.js
index 397fc9a..c1339cf 100644
--- a/app/static/js/services/soundfontPlayer.js
+++ b/app/static/js/services/soundfontPlayer.js
@@ -42,26 +42,41 @@
         // ── SpessaSynth init ──
         init: async function (audioContext) {
             if (_initialized && _synthInstance) return;
-            if (!window.SpessaSynthClass) {
-                console.warn("[SonicSF] SpessaSynth not loaded yet. Retrying in 1s...");
-                // Retry once after module script loads
+            if (!window.SpessaSynthClass || !window.__SpessaSynthCDN) {
+                console.warn("[SonicSF] SpessaSynth not loaded yet. Retrying in 2s...");
                 setTimeout(() => {
                     if (!_initialized && window.SpessaSynthClass && audioContext) {
                         this.init(audioContext);
                     }
-                }, 1000);
+                }, 2000);
                 return;
             }
             try {
-                _synthInstance = new window.SpessaSynthClass(audioContext.destination);
+                // Register the AudioWorklet processor from CDN
+                const procUrl = window.__SpessaSynthCDN + "spessasynth_processor.min.js";
+                await audioContext.audioWorklet.addModule(procUrl);
+                // Create WorkletSynthesizer
+                _synthInstance = new window.SpessaSynthClass(audioContext);
+                // Wait for synth to be ready (loads default soundbank)
+                await _synthInstance.isReady;
                 _initialized = true;
-                console.log("[SonicSF] SpessaSynth initialized.");
+                console.log("[SonicSF] SpessaSynth initialized via AudioWorklet.");
                 // Auto-load default SF3
                 if (_currentSfId === null) {
                     this.loadSoundFont("sgm_v2.01");
                 }
             } catch (e) {
-                console.error("[SonicSF] SpessaSynth init failed:", e);
+                console.warn("[SonicSF] SpessaSynth AudioWorklet init failed:", e, "- trying WorkerSynthesizer...");
+                try {
+                    const { WorkerSynthesizer } = await import(window.__SpessaSynthCDN + "index.js");
+                    _synthInstance = new WorkerSynthesizer(audioContext);
+                    await _synthInstance.isReady;
+                    _initialized = true;
+                    console.log("[SonicSF] SpessaSynth initialized via Worker.");
+                    if (_currentSfId === null) this.loadSoundFont("sgm_v2.01");
+                } catch (e2) {
+                    console.error("[SonicSF] SpessaSynth init failed completely:", e2);
+                }
             }
         },
 
@@ -89,11 +104,11 @@
                 }
             }
             try {
-                await _synthInstance.soundFontManager.addSoundFont(buffer);
+                await _synthInstance.soundBankManager.addSoundBank(buffer, sfId);
                 _currentSfId = sfId;
                 console.log("[SonicSF] SoundFont loaded:", sfId);
             } catch (e) {
-                console.error("[SonicSF] Error parsing SF3:", e);
+                console.error("[SonicSF] Error parsing SF in SpessaSynth:", e);
             }
         },
 
diff --git a/app/templates/index.html b/app/templates/index.html
index ffcc05f..f5ce43e 100644
--- a/app/templates/index.html
+++ b/app/templates/index.html
@@ -11,8 +11,9 @@
     <script src="https://unpkg.com/react@18.3.1/umd/react.production.min.js"></script>
     <script src="https://unpkg.com/react-dom@18.3.1/umd/react-dom.production.min.js"></script>
     <script type="module">
-      import { Synthesizer } from 'https://cdn.jsdelivr.net/npm/spessasynth_lib@latest/dist/spessasynth_lib.js';
-      window.SpessaSynthClass = Synthesizer;
+      import { WorkletSynthesizer } from 'https://cdn.jsdelivr.net/npm/spessasynth_lib@4.3.1/dist/index.js';
+      window.SpessaSynthClass = WorkletSynthesizer;
+      window.__SpessaSynthCDN = 'https://cdn.jsdelivr.net/npm/spessasynth_lib@4.3.1/dist/';
       console.log('[SonicSF] SpessaSynth library loaded.');
     </script>
     <script src="/static/js/services/api.js?v=202607232105"></script>