Mike, I can't answer that one and I don't know if I want to try since I would have to spend at least a couple of hours on my knees and and tons of sweat to add new RCA cables; unless it's Reaaally worth it! I read in other threads that people came to the same conclusion as yours...
I installed tonight a new optical cable (coax) between my cable SA2100 box and my receiver to get DD 5.1 or ProLogic. HBO brodcasted "The Perfect Storm" with DD5.1. I experienced something that probably others encountered: The sound was not in phase with the image.
My guess it's because the video is fed thru VCR end PVR (which of course have no optical input)unlike the sound signal that goes straight to the optical input of my receiver. I noticed before that I had a couple of seconds of delay between my Home theater and the TV in my kitchen when there're on the same channel...

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