I use a Linksys Music Bridge between my PC and my 990. The Music Bridge has both coax and optical digital outputs. I've used a couple of different music programs but settled on iTunes. I now rip my music in lossless AIFF format (with the iTunes correction feature on). Ripping to AIFF takes a significant amount of space but with hard drives so cheap (1TB for $275) ripping to WAV or AIFF is no big deal now.

To control iTunes there are now a couple of options. The iTouch and iPhone both have software available that will turn them into remotes for iTunes assuming you have a Mac computer. For those with PCs the Keyspan's Tuneview RF remote mimics the iTunes music library, including playlists.

Good luck with your search.