I didn't test different sampling frequencies yet, but I want to try out 48kHz in the next days. I tested different bIntervals by just changing the value AUDIO_POLLING_INTERVAL_480 in usb_desk.h for testing purposes (Manually setting the value is normally not necessary). Or also by setting the AUDIO_SUBSLOT_SIZE to 3 (24bit per samples). Then 1059bytes/ms are required at 8channels/44.1kHz.