I would not discount Sonos so quickly. If you add a Synchro-Mesh reclocker between Sonos and your DAC, this can make all the difference. Sonos is a great platform for redbook playback. However, it delivers the bits with some jitter. Then you just need a good de-jittering device and a good S/DIF coax cable. I can provide both of these. IT even has a path to audio nirvana. Add the Hynes-based linear supply "Dynamo" along with my Coax cable and you have world-class source.
Steve N.
Empirical Audio