diff --git a/module_usb_aud_shared/audio.xc b/module_usb_aud_shared/audio.xc
index 42cbd908..811832cc 100755
--- a/module_usb_aud_shared/audio.xc
+++ b/module_usb_aud_shared/audio.xc
@@ -60,7 +60,7 @@ extern void device_reboot(void);
 
 /* I2S delivery thread */
 #pragma unsafe arrays
-unsigned deliver(chanend c_out, chanend c_spd_out, unsigned divide, chanend ?c_dig_rx)
+unsigned deliver(chanend c_out, chanend ?c_spd_out, unsigned divide, chanend ?c_dig_rx)
 {
 	unsigned sample;
 #if NUM_USB_CHAN_OUT > 0 
@@ -515,7 +515,9 @@ static unsigned dummy_deliver(chanend c_out) {
 
 void audio(chanend c_mix_out, chanend ?c_dig_rx, chanend ?c_config) 
 {
+#ifdef SPDIF
     chan c_spdif_out;
+#endif
     unsigned curSamFreq = DEFAULT_FREQ;
     unsigned mClk;
     unsigned divide;
@@ -589,7 +591,13 @@ void audio(chanend c_mix_out, chanend ?c_dig_rx, chanend ?c_config)
                 outuint(c_spdif_out, mClk);
 #endif 
 
-                curSamFreq = deliver(c_mix_out, c_spdif_out, divide, c_dig_rx);
+                curSamFreq = deliver(c_mix_out,
+#ifdef SPDIF
+                   c_spdif_out,
+#else
+                   null,
+#endif 
+                   divide, c_dig_rx);
 
                 // Currently no more audio will happen after this point
                 if (curSamFreq == AUDIO_STOP_FOR_DFU) 
diff --git a/module_usb_aud_shared/endpoint0/audiorequests.xc b/module_usb_aud_shared/endpoint0/audiorequests.xc
index f14ecc3d..52ab38e3 100644
--- a/module_usb_aud_shared/endpoint0/audiorequests.xc
+++ b/module_usb_aud_shared/endpoint0/audiorequests.xc
@@ -35,6 +35,7 @@ extern int volsIn[];
 extern unsigned int mutesIn[];
 
 /* Mixer settings */
+#ifdef MIXER
 extern unsigned char mixer1Crossbar[];
 extern short mixer1Weights[];
 
@@ -48,6 +49,7 @@ extern unsigned char channelMapUsb[NUM_USB_CHAN_IN];
 
 /* Mixer input mapping */
 extern unsigned char mixSel[MIX_INPUTS];
+#endif
 
 /* Global var for current frequency */
 extern unsigned int g_curSamFreq;
diff --git a/module_usb_aud_shared/endpoint0/endpoint0.xc b/module_usb_aud_shared/endpoint0/endpoint0.xc
index ba897759..393d670e 100755
--- a/module_usb_aud_shared/endpoint0/endpoint0.xc
+++ b/module_usb_aud_shared/endpoint0/endpoint0.xc
@@ -63,6 +63,7 @@ int volsIn[NUM_USB_CHAN_IN + 1];
 unsigned int mutesIn[NUM_USB_CHAN_IN + 1];
 //unsigned int multIn[NUM_USB_CHAN_IN + 1];
 
+#ifdef MIXER
 unsigned char mixer1Crossbar[18];
 short mixer1Weights[18*8];
 //#define MAX_MIX_COUNT 8
@@ -75,6 +76,7 @@ unsigned char channelMapAud[NUM_USB_CHAN_OUT];
 unsigned char channelMapUsb[NUM_USB_CHAN_IN];
 #endif
 unsigned char mixSel[MIX_INPUTS];
+#endif
 
 int min(int x, int y);
 
@@ -161,6 +163,7 @@ void Endpoint0( chanend c_ep0_out, chanend c_ep0_in, chanend c_audioControl,
         mutesIn[i] = 0;
     }
 
+#ifdef MIXER
     /* Set up mixer default state */
     for (int i = 0; i < 18*8; i++) {
       mixer1Weights[i] = 0x8001; //-inf
@@ -210,6 +213,7 @@ void Endpoint0( chanend c_ep0_out, chanend c_ep0_in, chanend c_audioControl,
     {
         mixSel[i] = i;
     }
+#endif
 
     /* Copy langIDs string desc into string[0] */
     /* TODO: Macro? */
diff --git a/module_usb_aud_shared/usb_buffer/decouple.xc b/module_usb_aud_shared/usb_buffer/decouple.xc
index 861f2b0f..8c73e1c0 100644
--- a/module_usb_aud_shared/usb_buffer/decouple.xc
+++ b/module_usb_aud_shared/usb_buffer/decouple.xc
@@ -165,17 +165,21 @@ static inline void swap(xc_ptr &a, xc_ptr &b)
 }
 
 // shared global midi buffering variables
+#ifdef MIDI
 unsigned g_midi_from_host_flag = 0;
 unsigned g_midi_to_host_flag = 0;
 int midi_to_host_usb_ep = 0;
 int midi_from_host_usb_ep = 0;
+#endif
 int aud_from_host_usb_ep = 0;
 int aud_to_host_usb_ep = 0;
 int int_usb_ep = 0;
 
+#ifdef MIDI
 unsigned int g_midi_to_host_buffer_A[MAX_USB_MIDI_PACKET_SIZE/4+4];
 unsigned int g_midi_to_host_buffer_B[MAX_USB_MIDI_PACKET_SIZE/4+4];
 int g_midi_from_host_buffer[MAX_USB_MIDI_PACKET_SIZE+4];
+#endif
 
 // shared global aud buffering variables
 
diff --git a/module_usb_aud_shared/usb_buffer/usb_buffer.xc b/module_usb_aud_shared/usb_buffer/usb_buffer.xc
index 16f8d177..2ef11e36 100644
--- a/module_usb_aud_shared/usb_buffer/usb_buffer.xc
+++ b/module_usb_aud_shared/usb_buffer/usb_buffer.xc
@@ -85,7 +85,9 @@ void buffer(register chanend c_aud_out, register chanend c_aud_in, chanend c_aud
   XUD_ep ep_midi_from_host = XUD_Init_Ep(c_midi_from_host);
   XUD_ep ep_midi_to_host = XUD_Init_Ep(c_midi_to_host);
 #endif
+#if defined(SPDIF_RX) || defined(ADAT_RX)
   XUD_ep ep_int = XUD_Init_Ep(c_int);
+#endif
   
     unsigned datalength;
     unsigned tmp;
@@ -116,7 +118,9 @@ void buffer(register chanend c_aud_out, register chanend c_aud_in, chanend c_aud
     
     set_thread_fast_mode_on();
 
+#if defined(SPDIF_RX) || defined(ADAT_RX)
     asm("stw %0, dp[int_usb_ep]"::"r"(ep_int));    
+#endif
     asm("stw %0, dp[aud_from_host_usb_ep]"::"r"(ep_aud_out));
     asm("stw %0, dp[aud_to_host_usb_ep]"::"r"(ep_aud_in));
     asm("stw %0, dp[buffer_aud_ctl_chan]"::"r"(c_aud_ctl));    
@@ -195,6 +199,7 @@ void buffer(register chanend c_aud_out, register chanend c_aud_in, chanend c_aud
         /* Wait for response from XUD and service relevant EP */
         select
         {
+#if defined(SPDIF_RX) || defined(ADAT_RX)
             /* Interrupt EP, send back interrupt data.  Note, request made from decouple */
             case inuint_byref(c_int, tmp):
             { 
@@ -221,6 +226,7 @@ void buffer(register chanend c_aud_out, register chanend c_aud_in, chanend c_aud
                 XUD_SetNotReady(ep_int);
                 break;
               }
+#endif
 
             /* Sample Freq our chan count update from ep 0 */     
             case inuint_byref(c_aud_ctl, tmp):