diff --git a/src/gb/audio.c b/src/gb/audio.c
index a0e5ef1b9..f356f45b8 100644
--- a/src/gb/audio.c
+++ b/src/gb/audio.c
@@ -576,47 +576,47 @@ void GBAudioUpdateFrame(struct GBAudio* audio, struct mTiming* timing) {
 }
 
 void GBAudioSamplePSG(struct GBAudio* audio, int16_t* left, int16_t* right) {
-	int dcOffset = audio->style == GB_AUDIO_GBA ? 0 : 0x8;
+	int dcOffset = audio->style == GB_AUDIO_GBA ? 0 : -0x8;
 	int sampleLeft = dcOffset;
 	int sampleRight = dcOffset;
 
 	if (audio->playingCh1 && !audio->forceDisableCh[0]) {
 		if (audio->ch1Left) {
-			sampleLeft -= audio->ch1.sample;
+			sampleLeft += audio->ch1.sample;
 		}
 
 		if (audio->ch1Right) {
-			sampleRight -= audio->ch1.sample;
+			sampleRight += audio->ch1.sample;
 		}
 	}
 
 	if (audio->playingCh2 && !audio->forceDisableCh[1]) {
 		if (audio->ch2Left) {
-			sampleLeft -=  audio->ch2.sample;
+			sampleLeft +=  audio->ch2.sample;
 		}
 
 		if (audio->ch2Right) {
-			sampleRight -= audio->ch2.sample;
+			sampleRight += audio->ch2.sample;
 		}
 	}
 
 	if (audio->playingCh3 && !audio->forceDisableCh[2]) {
 		if (audio->ch3Left) {
-			sampleLeft -= audio->ch3.sample;
+			sampleLeft += audio->ch3.sample;
 		}
 
 		if (audio->ch3Right) {
-			sampleRight -= audio->ch3.sample;
+			sampleRight += audio->ch3.sample;
 		}
 	}
 
 	if (audio->playingCh4 && !audio->forceDisableCh[3]) {
 		if (audio->ch4Left) {
-			sampleLeft -= audio->ch4.sample;
+			sampleLeft += audio->ch4.sample;
 		}
 
 		if (audio->ch4Right) {
-			sampleRight -= audio->ch4.sample;
+			sampleRight += audio->ch4.sample;
 		}
 	}
 
@@ -632,8 +632,8 @@ static void _sample(struct mTiming* timing, void* user, uint32_t cyclesLate) {
 	int16_t sampleLeft = 0;
 	int16_t sampleRight = 0;
 	GBAudioSamplePSG(audio, &sampleLeft, &sampleRight);
-	sampleLeft = (sampleLeft * audio->masterVolume * 9) >> 7;
-	sampleRight = (sampleRight * audio->masterVolume * 9) >> 7;
+	sampleLeft = (sampleLeft * audio->masterVolume * 6) >> 7;
+	sampleRight = (sampleRight * audio->masterVolume * 6) >> 7;
 
 	mCoreSyncLockAudio(audio->p->sync);
 	unsigned produced;
diff --git a/src/gba/audio.c b/src/gba/audio.c
index 14f47ff56..c0ed7cf4c 100644
--- a/src/gba/audio.c
+++ b/src/gba/audio.c
@@ -253,7 +253,7 @@ static int _applyBias(struct GBAAudio* audio, int sample) {
 	} else if (sample < 0) {
 		sample = 0;
 	}
-	return ((sample - GBARegisterSOUNDBIASGetBias(audio->soundbias)) * audio->masterVolume) >> 2;
+	return ((sample - GBARegisterSOUNDBIASGetBias(audio->soundbias)) * audio->masterVolume * 3) >> 4;
 }
 
 static void _sample(struct mTiming* timing, void* user, uint32_t cyclesLate) {