I just finished switching to a Sonos setup for my house and my two channel system. I have three ZP80s and four ZP 100s, all of which run nine sets of speakers in seven zones. I looked at integrating my current Crestron controller to provide whole house audio, but it was going to cost $30,000, whereas the current arrangement cost less than $4500.
For my two channel system, I have a ZP80 with its coaxial digital output going into the Sim Audio Evolution SuperNova CD player to take advantage of the Sim's DAC. The balanced outputs of the Sim then go to the pre-amp (BAT-51SE) and then out to Parasound JC-1 monoblocks. I rippped my CD collection to a Buffalo Technologies NAS drive using Apple Lossless.
If I put a CD in the SuperNova CD player and switch up and back between using its transport and using the "digital in" input fed by the ZP80, I can't tell the difference. I invited my friend "high end Dave" (Mr. MBL 101E) over for a listen and his jaw dropped. He decided to sell his analog gear and get rid of CDs.
I couldn't be happier with the Sonos system. The controllers are fantastic, Rhapsody is great, and now that my CD collection is in a box, I don't have to mess with discs anymore. The ZP-100s drive in-wall and in-ceiling speakers just great-- but I also have a ZP-100 in my bedroom driving B&W CDM-1-SE speakers and an M&K subwoofer-- and the ZP-100 can drive this gear with power to spare.
If Sonos came out with a unit that had a USB output, I might be tempted to replace my Sim SuperNova CD player with a DAC that had a USB input, but right now the SuperNova's DAC performs spectacularly well and it is occasionally nice to be able to test drive a CD in the transport.
The access to organized music files, new releases, top artists and tracks, and different genres is great. Being able to play different music in every room or the same tunes everywhere is also great--- all through a controller that my wife and kids can use without my help (priceless!)