Hello - I did an auto-scan and ended up with about 8 HD channels on Comcast in Nashville, TN. Only the onboard TV speakers have audio on these channels. There's nothing coming out of the digital audio out as far as I can tell. Can anyone explain this?? The "normal" channels all output to my receiver. Am I doing something wrong?? Thanks.

It is probably your HDTV. Many cannot output 5.1 from the fiber optic hookup. My TV does stereo from it. You can probably check your manual and find out if that is it. It may not be able to down rez the audio.