diff --git a/src/common.h b/src/common.h
index 0d7b57b..ebe5561 100644
--- a/src/common.h
+++ b/src/common.h
@@ -102,6 +102,7 @@ void platform_turbo(void);
 void platform_refresh(bool *sq, bool *css, bool *vox);
 bool platform_poke(uint8_t addr, uint8_t reg, uint16_t val);
 void platform_amp_enable(bool state);
+void platform_audio_enable(bool state);
 
 /*
  * UART peripheral control
diff --git a/src/r5f1026a/platform.c b/src/r5f1026a/platform.c
index 4004bc6..04aaaee 100644
--- a/src/r5f1026a/platform.c
+++ b/src/r5f1026a/platform.c
@@ -385,9 +385,9 @@ void platform_init(void) {
   P1_bit.no0 = 0;   // P10 (RXEN) is low
   PM1_bit.no0 = 0;  // P10 (RXEN) is output
 
-  ADPC |= 0x01;     // P20-P23 are digital I/O
+  ADPC = 0x01;      // P20-P23 are digital I/O
 
-  P2_bit.no0 = 1;   // P20 (SQ) is high
+  P2_bit.no0 = 0;   // P20 (SQ) is low
   PM2_bit.no0 = 0;  // P20 (SQ) is output
 
   P2_bit.no1 = 1;   // P21 (H/L) is high
@@ -434,9 +434,7 @@ void platform_turbo(void) {
 }
 
 void platform_refresh(bool *sq, bool *css, bool *vox) {
-  *sq = P2_bit.no3;  // Squelch status from internal AT1846S
-  P2_bit.no0 = !*sq; // Squelch status to external pin
-
+  *sq = P2_bit.no3;   // Squelch status from internal AT1846S
   *css = P1_bit.no4;  // CSS status from internal AT1846S
   *vox = P13_bit.no7; // VOX status from internal AT1846S
 }
@@ -471,3 +469,13 @@ void platform_amp_enable(bool state) {
     P2_bit.no1 = 1;   // P21 (H/L) is high
   }
 }
+
+void platform_audio_enable(bool state) {
+  if (state) {
+    // Enable external audio amplifier
+    P2_bit.no0 = 0;   // P20 (SQ) is low
+  } else {
+    // Disable external audio amplifier
+    P2_bit.no0 = 1;   // P20 (SQ) is high
+  }
+}
diff --git a/src/sa8x8.c b/src/sa8x8.c
index ffe90a7..be5b563 100644
--- a/src/sa8x8.c
+++ b/src/sa8x8.c
@@ -24,6 +24,7 @@ const char CMD_TURBO[] = "+TURBO";
 const char CMD_PEEK[] = "+PEEK=";
 const char CMD_POKE[] = "+POKE=";
 const char CMD_AMP[] = "+AMP=";
+const char CMD_AUDIO[] = "+AUDIO=";
 
 const char VERSION[] = "sa8x8-fw/" GIT_INFO "\r\n";
 const char MODEL[] = MODULE_MODEL "\r\n";
@@ -321,6 +322,28 @@ int main(void) {
       continue;
     }
 
+    // AT+AUDIO=<0,1>: Set external audio amplifier state
+    if (eq(&cmd[2], (char *)CMD_AUDIO, sizeof(CMD_AUDIO) - 1)) {
+      uint8_t i = sizeof(CMD_AUDIO) + 1;
+
+      // Parse state
+      bool state = (bool) a2i(cmd, &i);
+
+      // Error if missing terminator
+      if (!(cmd[i] == '\0')) {
+        uart_puts(ERR);
+        continue;
+      }
+
+      // Set requested amplifier state
+      platform_audio_enable(state);
+
+      // Send command valid response
+      uart_puts(OK);
+
+      continue;
+    }
+
     // All other requests are errors
     uart_puts(ERR);
   }