diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 0dcbab5f..3d6e5199 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -16,6 +16,8 @@ UNRELEASED
   * CHANGED:   aud_to_host buffer size and the condition to come out of underflow
     in decoupler to fix buffer underflow seen in ADAT tests
   * FIXED:     Initialise SMUX based on DEFAULT_FREQ in clockgen
+  * FIXED:     Update g_numUsbChan_Out to the number of channels for the selected
+    interface when receiving a set interface request over EP0
 
 4.0.0
 -----
diff --git a/lib_xua/src/core/buffer/decouple/decouple.xc b/lib_xua/src/core/buffer/decouple/decouple.xc
index b5405fa2..4b7dc0cf 100644
--- a/lib_xua/src/core/buffer/decouple/decouple.xc
+++ b/lib_xua/src/core/buffer/decouple/decouple.xc
@@ -155,68 +155,65 @@ unsigned unpackData = 0;
 unsigned packState = 0;
 unsigned packData = 0;
 
-static inline void SendSamples4(chanend c_mix_out)
+static inline void _send_sample_4(chanend c_mix_out, int ch)
 {
-    /* Doing this checking allows us to unroll */
-    if(g_numUsbChan_Out == NUM_USB_CHAN_OUT)
-    {
-        /* Buffering not underflow condition send out some samples...*/
-#pragma loop unroll
-        for(int i = 0; i < NUM_USB_CHAN_OUT; i++)
-        {
-            int sample;
-            int mult;
-            int h;
-            unsigned l;
-
-            read_via_xc_ptr(sample, g_aud_from_host_rdptr);
-            g_aud_from_host_rdptr+=4;
+    int sample;
+    read_via_xc_ptr(sample, g_aud_from_host_rdptr);
+    g_aud_from_host_rdptr+=4;
 
 #if (OUTPUT_VOLUME_CONTROL == 1) && (!OUT_VOLUME_IN_MIXER)
-            unsafe
-            {
-                mult = multOutPtr[i];
-            }
-            {h, l} = macs(mult, sample, 0, 0);
-            h <<= 3;
+    int mult;
+    int h;
+    unsigned l;
+    unsafe
+    {
+        mult = multOutPtr[ch];
+    }
+    {h, l} = macs(mult, sample, 0, 0);
+    h <<= 3;
 #if (STREAM_FORMAT_OUTPUT_RESOLUTION_32BIT_USED == 1)
-            h |= (l >>29) & 0x7; // Note: This step is not required if we assume sample depth is 24bit (rather than 32bit)
-                                 // Note: We need all 32bits for Native DSD
+    h |= (l >>29) & 0x7; // Note: This step is not required if we assume sample depth is 24bit (rather than 32bit)
+                            // Note: We need all 32bits for Native DSD
 #endif
-            outuint(c_mix_out, h);
+    outuint(c_mix_out, h);
 #else
-            outuint(c_mix_out, sample);
+    outuint(c_mix_out, sample);
 #endif
+}
+
+static inline void SendSamples4(chanend c_mix_out)
+{
+    /* Doing this allows us to unroll */
+    if(g_numUsbChan_Out == HS_STREAM_FORMAT_OUTPUT_1_CHAN_COUNT)
+    {
+        #pragma loop unroll
+        for(int i = 0; i < HS_STREAM_FORMAT_OUTPUT_1_CHAN_COUNT; i++)
+        {
+            _send_sample_4(c_mix_out, i);
+        }
+    }
+    else if(g_numUsbChan_Out == HS_STREAM_FORMAT_OUTPUT_2_CHAN_COUNT)
+    {
+        #pragma loop unroll
+        for(int i = 0; i < HS_STREAM_FORMAT_OUTPUT_2_CHAN_COUNT; i++)
+        {
+            _send_sample_4(c_mix_out, i);
+        }
+    }
+    else if(g_numUsbChan_Out == HS_STREAM_FORMAT_OUTPUT_3_CHAN_COUNT)
+    {
+        #pragma loop unroll
+        for(int i = 0; i < HS_STREAM_FORMAT_OUTPUT_3_CHAN_COUNT; i++)
+        {
+            _send_sample_4(c_mix_out, i);
         }
     }
     else
     {
-#pragma loop unroll
+        #pragma loop unroll
         for(int i = 0; i < NUM_USB_CHAN_OUT_FS; i++)
         {
-            int sample;
-            int mult;
-            int h;
-            unsigned l;
-
-            read_via_xc_ptr(sample, g_aud_from_host_rdptr);
-            g_aud_from_host_rdptr+=4;
-
-#if (OUTPUT_VOLUME_CONTROL == 1) && (!OUT_VOLUME_IN_MIXER)
-            unsafe
-            {
-                mult = multOutPtr[i];
-            }
-            {h, l} = macs(mult, sample, 0, 0);
-            h <<= 3;
-#if (STREAM_FORMAT_OUTPUT_RESOLUTION_32BIT_USED == 1)
-            h |= (l >>29) & 0x7; // Note: This step is not required if we assume sample depth is 24bit (rather than 32bit)
-                                 // Note: We need all 32bits for Native DSD
-#endif
-            outuint(c_mix_out, h);
-#else
-            outuint(c_mix_out, sample);
-#endif
+            _send_sample_4(c_mix_out, i);
         }
     }
 }
diff --git a/lib_xua/src/core/endpoint0/xua_endpoint0.c b/lib_xua/src/core/endpoint0/xua_endpoint0.c
index 1f23a457..d0645380 100755
--- a/lib_xua/src/core/endpoint0/xua_endpoint0.c
+++ b/lib_xua/src/core/endpoint0/xua_endpoint0.c
@@ -245,7 +245,6 @@ const unsigned g_dataFormat_In[INPUT_FORMAT_COUNT]      = {STREAM_FORMAT_INPUT_1
 };
 
 /* Channel count */
-/* Note, currently only input changes.. */
 const unsigned g_chanCount_In_HS[INPUT_FORMAT_COUNT]       = {HS_STREAM_FORMAT_INPUT_1_CHAN_COUNT,
 #if(INPUT_FORMAT_COUNT > 1)
                                                             HS_STREAM_FORMAT_INPUT_2_CHAN_COUNT,
@@ -255,6 +254,15 @@ const unsigned g_chanCount_In_HS[INPUT_FORMAT_COUNT]       = {HS_STREAM_FORMAT_I
 #endif
 };
 
+const unsigned g_chanCount_Out_HS[OUTPUT_FORMAT_COUNT]       = {HS_STREAM_FORMAT_OUTPUT_1_CHAN_COUNT,
+#if(OUTPUT_FORMAT_COUNT > 1)
+                                                            HS_STREAM_FORMAT_OUTPUT_2_CHAN_COUNT,
+#endif
+#if(OUTPUT_FORMAT_COUNT > 2)
+                                                            HS_STREAM_FORMAT_OUTPUT_3_CHAN_COUNT
+#endif
+};
+
 XUD_ep ep0_out;
 XUD_ep ep0_in;
 
@@ -580,7 +588,7 @@ void XUA_Endpoint0_loop(XUD_Result_t result, USB_SetupPacket_t sp, chanend c_ep0
 
                                     if(g_curUsbSpeed == XUD_SPEED_HS)
                                     {
-                                        outuint(c_audioControl, NUM_USB_CHAN_OUT);                 /* Channel count */
+                                        outuint(c_audioControl, g_chanCount_Out_HS[sp.wValue-1]);                 /* Channel count */
                                         outuint(c_audioControl, g_subSlot_Out_HS[sp.wValue-1]);    /* Subslot */
                                         outuint(c_audioControl, g_sampRes_Out_HS[sp.wValue-1]);    /* Resolution */
                                     }