Although it isn't as nice as an optical from the soundcard to the reciver, this little gadget has treated me pretty well the last few weeks:
http://www.amazon.com/Western-Digital-Media-Player-WDBAAL0000NBK-NESN/dp/B002KG0JMG
The Pros:
Less than 60 bucks
Works with most any external USB Driven device, even thumb drives
Plays flac, mp3, wav, aac, and a couple of other audio codecs I care nothing about.
Plays VOB, avi, xvid, and a couple of other video codecs I care nothing about.
Optical out
The Cons:
No Support for 24 Bit
Not truly gapless (like an mp3 player type cut between tracks)
The thing is really tiny and fits great into my system. Nice and affordable.