Figured I would throw this out there in case anyone else finds it useful: I wrote a small program to basically turn my PC into a poor man's surround sound receiver.
My computer is the center of my room. It's hooked directly up to my sound system (no receiver; straight PC to amplifier). I also use my monitor for playing Xbox, so I had the audio from the Xbox coming into my PC via line-in so I can play it back through my main speakers.
I wanted to get surround sound from my Xbox, so the only way to really do this is to send DD 5.1 (AC3) via the optical port into my PC, which then decodes it into 5.1 for playback via my soundcard.
S/PDIF inputs in general are finicky, let alone capturing bit-perfect samples from one so that a compressed bitstream can be decoded, but nevertheless, it works.
GPLv3 source code is at: