The biggest issue (for either a laptop through the 990's USB port or a Squeezebox) is going to be the source data - raw WAV, lossless compression (such as FLAC), or some various levels of lossy compression via MP3, AAC, or WMA. The software handling playback on a laptop and the 990's USB signal path would also factor in, as would the SlimServer software and Squeezebox hardware if that was your delivery method.

I've read a number of discussions regarding comparisons between CD playback and the various lossless and lossy means of moving data to a hard drive. If I do pick up a SoundBridge (or some other similar device), I plan to conduct some tests of my own. I have tried the output of my iPod Nano's headphone jack through my 990, and that was definitely a step down in sound quality from the original CD - but I haven't tried bypassing the iPod's headphone output (need a docking cradle for that) and I've been told that the direct analog output (without the headphone amp in the signal path) is a bit better. Some folks say that anything above about a 200kbps bit rate will yield near-CD quality, but I'm a bit dubious of that personally. To really approach CD quality, I'd lean toward lossless compression (like FLAC) or even simply using the raw data (in WAV format). Storing everything as WAV files would be space-intensive, but it would let you pretty readily generate lossy compression copies for use with portable players.