diff --git a/module_usb_audio/devicedefines.h b/module_usb_audio/devicedefines.h
index 58934e02..d1420956 100644
--- a/module_usb_audio/devicedefines.h
+++ b/module_usb_audio/devicedefines.h
@@ -66,22 +66,22 @@
 #define MAX_FREQ_A1              MAX_FREQ
 #endif
 
-/* For Audio Class 1.0 we always have at most 2 channels */
+/* For Audio Class 1.0 and Full-speed Audio 2.0 we always have at most 2 channels */
 #if (NUM_USB_CHAN_OUT > 2)
-#define NUM_USB_CHAN_OUT_A1  (2)
+#define NUM_USB_CHAN_OUT_FS  (2)
 #else
-#define NUM_USB_CHAN_OUT_A1  (NUM_USB_CHAN_OUT)
+#define NUM_USB_CHAN_OUT_FS  (NUM_USB_CHAN_OUT)
 #endif
 
 #if (NUM_USB_CHAN_IN > 2)
-#define NUM_USB_CHAN_IN_A1  (2)
+#define NUM_USB_CHAN_IN_FS (2)
 #else
-#define NUM_USB_CHAN_IN_A1  (NUM_USB_CHAN_IN)
+#define NUM_USB_CHAN_IN_FS  (NUM_USB_CHAN_IN)
 #endif
 
-/* Channel count defines for FS mode */
-#define NUM_USB_CHAN_OUT_FS     (NUM_USB_CHAN_OUT_A1)
-#define NUM_USB_CHAN_IN_FS      (NUM_USB_CHAN_IN_A1)
+/* Channel count defines for Audio 1.0 mode */
+//#define NUM_USB_CHAN_OUT_A1     (NUM_USB_CHAN_OUT_FS)
+//#define NUM_USB_CHAN_IN_A1      (NUM_USB_CHAN_IN_FS)
 
 
 #if defined(IO_EXPANSION) && (IO_EXPANSION == 0)
diff --git a/module_usb_audio/endpoint0/endpoint0.xc b/module_usb_audio/endpoint0/endpoint0.xc
index 195467ef..57de6391 100755
--- a/module_usb_audio/endpoint0/endpoint0.xc
+++ b/module_usb_audio/endpoint0/endpoint0.xc
@@ -278,7 +278,7 @@ void Endpoint0( chanend c_ep0_out, chanend c_ep0_in, chanend c_audioControl,
                                     else
                                     {
                                         outuint(c_audioControl, SET_CHAN_COUNT_OUT);
-                                        outuint(c_audioControl, NUM_USB_CHAN_OUT_A1);
+                                        outuint(c_audioControl, NUM_USB_CHAN_OUT_FS);
                                     }
 #ifdef NATIVE_DSD
                                     if(g_dsdMode)
@@ -324,7 +324,7 @@ void Endpoint0( chanend c_ep0_out, chanend c_ep0_in, chanend c_audioControl,
                                     else
                                     {
                                         outuint(c_audioControl, SET_CHAN_COUNT_IN);
-                                        outuint(c_audioControl, NUM_USB_CHAN_IN_A1);
+                                        outuint(c_audioControl, NUM_USB_CHAN_IN_FS);
                                     }
 #ifdef ADAT_RX
                                     outuint(c_clk_ctl, SET_SMUX);
diff --git a/module_usb_audio/usb_buffer/decouple.xc b/module_usb_audio/usb_buffer/decouple.xc
index aa7ad17f..82e4da54 100644
--- a/module_usb_audio/usb_buffer/decouple.xc
+++ b/module_usb_audio/usb_buffer/decouple.xc
@@ -10,16 +10,17 @@
 #endif
 #define MAX(x,y) ((x)>(y) ? (x) : (y))
 
-#define CLASS_TWO_PACKET_SIZE ((((MAX_FREQ+7999)/8000))+3) // Samples per channel
-#define CLASS_ONE_PACKET_SIZE  ((((MAX_FREQ_A1+999)/1000))+3) // Samples per channel
+#define CLASS_TWO_PACKET_SIZE ((((MAX_FREQ+7999)/8000))+3)     // Samples per channel
+#define CLASS_ONE_PACKET_SIZE  ((((MAX_FREQ_A1+999)/1000))+3)  // Samples per channel
 
+/* TODO user SLOTSIZE to potentially save memory */
+#define BUFF_SIZE_OUT MAX(4 * CLASS_TWO_PACKET_SIZE * NUM_USB_CHAN_OUT, 4 * CLASS_ONE_PACKET_SIZE * NUM_USB_CHAN_OUT_FS)
+#define BUFF_SIZE_IN  MAX(4 * CLASS_TWO_PACKET_SIZE * NUM_USB_CHAN_IN, 4 * CLASS_ONE_PACKET_SIZE * NUM_USB_CHAN_IN_FS)
 
-#define BUFF_SIZE_OUT MAX(4 * CLASS_TWO_PACKET_SIZE * NUM_USB_CHAN_OUT, 4 * CLASS_ONE_PACKET_SIZE * NUM_USB_CHAN_OUT_A1)
-#define BUFF_SIZE_IN  MAX(4 * CLASS_TWO_PACKET_SIZE * NUM_USB_CHAN_IN, 4 * CLASS_ONE_PACKET_SIZE * NUM_USB_CHAN_IN_A1)
-
+/* Maximum USB buffer size (1024 bytes + 1 word to store length) */
 #define MAX_USB_AUD_PACKET_SIZE 1028
 
-#define OUT_BUFFER_PREFILL (MAX(NUM_USB_CHAN_OUT_A1*CLASS_ONE_PACKET_SIZE*3+4,NUM_USB_CHAN_OUT*CLASS_TWO_PACKET_SIZE*4+4)*1)
+#define OUT_BUFFER_PREFILL (MAX(NUM_USB_CHAN_OUT_FS*CLASS_ONE_PACKET_SIZE*3+4,NUM_USB_CHAN_OUT*CLASS_TWO_PACKET_SIZE*4+4)*1)
 #define IN_BUFFER_PREFILL (MAX(CLASS_ONE_PACKET_SIZE*3+4,CLASS_TWO_PACKET_SIZE*4+4)*2)
 
 /* Volume and mute tables */
@@ -37,7 +38,7 @@ unsigned g_numUsbChanOut = NUM_USB_CHAN_OUT;
 unsigned g_numUsbChanIn = NUM_USB_CHAN_IN;
 
 #define MAX_DEVICE_AUD_PACKET_SIZE_CLASS_TWO ((MAX_FREQ/8000+1)*NUM_USB_CHAN_IN*4)
-#define MAX_DEVICE_AUD_PACKET_SIZE_CLASS_ONE (((MAX_FREQ_A1/1000+1)*NUM_USB_CHAN_IN_A1*3)+4)
+#define MAX_DEVICE_AUD_PACKET_SIZE_CLASS_ONE (((MAX_FREQ_A1/1000+1)*NUM_USB_CHAN_IN_FS*3)+4)
 
 #define MAX_DEVICE_AUD_PACKET_SIZE (MAX(MAX_DEVICE_AUD_PACKET_SIZE_CLASS_ONE, MAX_DEVICE_AUD_PACKET_SIZE_CLASS_TWO))
 
@@ -745,8 +746,8 @@ void decouple(chanend c_mix_out,
 
         if(usb_speed == XUD_SPEED_FS)
         {
-            g_numUsbChanOut = NUM_USB_CHAN_OUT_A1;
-            g_numUsbChanIn = NUM_USB_CHAN_IN_A1;
+            g_numUsbChanOut = NUM_USB_CHAN_OUT_FS;
+            g_numUsbChanIn = NUM_USB_CHAN_IN_FS;
         }
     }
 
@@ -804,7 +805,7 @@ void decouple(chanend c_mix_out,
                     if (usb_speed == XUD_SPEED_HS)
                         mid*=NUM_USB_CHAN_IN*SAMPLE_SUBSLOT_SIZE_HS;
                     else
-                        mid*=NUM_USB_CHAN_IN_A1*SAMPLE_SUBSLOT_SIZE_FS;
+                        mid*=NUM_USB_CHAN_IN_FS*SAMPLE_SUBSLOT_SIZE_FS;
 
                     asm("stw %0, %1[0]"::"r"(mid),"r"(g_aud_to_host_zeros));
                 }