Fix clicky distortion - proper gain staging and reduced saturation

- Reduced channel gains: pulse 0.12, wave 0.18, noise 0.08
- Total max gain now ~1.0 instead of 2.7 (was clipping)
- More aggressive limiter: -12dB threshold, ratio 20
- Reduced saturation from 0.2-0.3 to 0.08-0.1 in all presets
- Should eliminate clicky distortion during playback

src-v2/audio/apu/APU.ts

@@ -97,33 +97,37 @@ export class GameBoyAPU {
   
   /**
    * Initialize all 8 channels with their gain nodes.
+   * 
+   * Gain staging: Keep total under 1.0 to avoid clipping
+   * With 8 channels potentially active: each should be ~0.1-0.15
    */
   private initializeChannels(): void {
-    // Create pulse channels
+    // Create pulse channels (4 × 0.12 = 0.48 max)
     for (const config of CHANNEL_CONFIG.pulse) {
-      const gain = this.createChannelGain(config.id, 0.25);
+      const gain = this.createChannelGain(config.id, 0.12);
       const channel = new PulseChannel(this.audioContext, gain, config.hasSweep);
       channel.setDutyCycle(config.defaultDuty);
       this.pulseChannels.set(config.id, channel);
       this.initChannelState(config.id);
     }
     
-    // Create wave channels (higher gain for bass)
+    // Create wave channels - slightly higher for bass presence (2 × 0.18 = 0.36 max)
     for (const config of CHANNEL_CONFIG.wave) {
-      const gain = this.createChannelGain(config.id, 0.55);  // Boosted for bass
+      const gain = this.createChannelGain(config.id, 0.18);
       const channel = new WaveChannel(this.audioContext, gain, config.preset);
       this.waveChannels.set(config.id, channel);
       this.initChannelState(config.id);
     }
     
-    // Create noise channels
+    // Create noise channels (2 × 0.08 = 0.16 max)
     for (const config of CHANNEL_CONFIG.noise) {
-      const gain = this.createChannelGain(config.id, 0.3);
+      const gain = this.createChannelGain(config.id, 0.08);
       const channel = new NoiseChannel(this.audioContext, gain, config.mode);
       this.noiseChannels.set(config.id, channel);
       this.initChannelState(config.id);
     }
   }
+  // Total max: 0.48 + 0.36 + 0.16 = 1.0
   
   /**
    * Create a gain node for a channel and connect to master.

src-v2/audio/effects/GameBoyColorizer.ts

@@ -34,7 +34,7 @@ const DEFAULT_CONFIG: ColorizerConfig = {
   lowpassFreq: 10000,     // GB natural rolloff (slightly higher)
   bitDepth: 8,            // Less aggressive bit crushing (4 was too harsh)
   sampleRateReduction: 1, // No sample rate reduction (was causing artifacts)
-  saturation: 0.2,        // Subtle warmth
+  saturation: 0.08,       // Very subtle - avoid clipping artifacts
   highpassFreq: 20,       // LOW - allow bass through!
 };
 
@@ -78,13 +78,13 @@ export class GameBoyColorizer {
     this.waveshaper.curve = this.createSaturationCurve(this.config.saturation);
     this.waveshaper.oversample = '2x';
     
-    // Limiter to prevent clipping
+    // Limiter to prevent clipping - more aggressive settings
     this.limiter = audioContext.createDynamicsCompressor();
-    this.limiter.threshold.value = -6;
-    this.limiter.knee.value = 6;
-    this.limiter.ratio.value = 12;
+    this.limiter.threshold.value = -12;  // Catch peaks earlier
+    this.limiter.knee.value = 3;         // Harder knee
+    this.limiter.ratio.value = 20;       // More aggressive limiting
     this.limiter.attack.value = 0.001;
-    this.limiter.release.value = 0.1;
+    this.limiter.release.value = 0.05;   // Faster release
     
     // Initialize chain (without bit crusher for now)
     this.initializeBasicChain();
@@ -227,13 +227,13 @@ export class GameBoyColorizer {
   static createPreset(preset: 'dmg' | 'gbc' | 'gba' | 'clean'): Partial<ColorizerConfig> {
     switch (preset) {
       case 'dmg':
-        // Original Game Boy - lo-fi but with bass
+        // Original Game Boy - warm but clean
         return {
           enabled: true,
           lowpassFreq: 8000,
           bitDepth: 8,           // Less harsh than 4-bit
           sampleRateReduction: 1, // No SR reduction (causes artifacts)
-          saturation: 0.3,
+          saturation: 0.1,       // Minimal saturation to avoid clicks
           highpassFreq: 30,      // Let bass through!
         };
         
@@ -244,7 +244,7 @@ export class GameBoyColorizer {
           lowpassFreq: 10000,
           bitDepth: 8,
           sampleRateReduction: 1,
-          saturation: 0.2,
+          saturation: 0.08,     // Minimal saturation
           highpassFreq: 25,
         };