I just had an HDTV-capable cable-TV box delivered. It has a coaxial digital output but the only spare digital-audio cables I had were optical. I used an old, spare RCA-type audio interconnect to hook it up to my home theater receiver. I'm not inclined to go spend 20 bucks on a "digital" interconnect since it works fine. Is there any fundamental difference? This is a very expensive (you know, oxygen-free multiply-shielded, gold-plated super-duper) interconnect that I have left over from the old days when I had a decent stereo setup.