Need a Block Diagram to verify the signal path on my XENYX 1204USB. I am using the RCA outputs to send the main mix to my speakers. When I playback audio from my PC via USB and select the red USB to Main button above the phones volume knob I get no audio output to the RCA Output, however I get it at the Main Output XLR's. I thought the signal path to the RCA outputs come from the same main output bus.

thanks,
Noel Fraticelli