The DVI wouldn't carry the audio, but have you tried connecting the audio portion of the cable box directly to the receiver white routing the video from the HD box to the TV through your current set-up?
I have a Samsung TX-P3071WH HDTV that I cannot connect to an external audio amplifer. I called Samsung today, and they stated "it should work", and that "I should take it in for service"....
I have tried connecting a receiver several times to no avail. My set up is a Pace HD cable box, connected w/HDMI (from box) to DVI input on TV. I tried analog audio cable from box to "DVI audio input". With this I have sound through the TV. I then connected RCA audio to "MONITOR OUT" audio to VIDEO IN on Sony STR-DE185 AV amp. No sound through amp, only through TV. I tried the DVD (component cabled, again only TV sound.
Today I tried the VCR (VIDEO INPUT-RCA composite), and got sound through the amp and TV (???).
I can make this work by cabling from the box & DVD into the amp, but I'd like to run it all through the TV for simplifying remote control programming. As an aside, I am able to do this with the other two Sony TVs w/no issue.
So, does this sound like a "service issue", or I am doing something wrong? Or, is it simply that it cannot be done under this set up?
Thanks for the help.