Personally I think that the reason for the difference in sound is the difference in the speed of light through glass rather than plastic. The digital "packets" maintain their "punch" and "zest" and "zing" and "pow" much better in glass and this translates into much cleaner, clearer, dynamic and punchy sound. It's for this reason that I use only glass fibre in my cold fusion-based perpetual motion machines!

Jeff Mackwood