Okay, so we all know that optical, coaxial and HDMI cables can transfer bitstream digital audio, to a reciever geared to decode this bitstream. I was just curious tho - we all use optical and coaxial for our 5.1 channel audio, and HDMI makes a big thing about it's ability to carry "up to 8 channels of uncompressed digital audio" - how much, or rather how many channels, can an optical/coaxial cable carry? Can they do 6.1? Can they do 7.1? (obviously as long as the source material has it and the reciever can decode it), could these cables do the same job as HDMI in the audio stakes? Whats the limitations of optical and coaxial cables, and why?