I've had 4 or 5 of their processors and never had a problem with it. I don't have an HD+ nearby to look at, but according to my VP30, while you are in the video source that you want to assign audio to, you go to "input adjust" and drop down to "audio input". Choose the appropriate coax or optical input. Enter or select. Then switch to the next video source and repeat. It should be that simple. Call DVDO. ALways helpful.