OK. After living with the Sonos system for a while now I have made the following oservations about sound quality:
Lossles sounds better. This is evident primarily as a loss of 'air/space' during playback of music saved in lossy formats (either wma vbr set for highest quality or 196 bit mp3) vs. flac. Some may not be able to appreciate this, but I suspect this is more a reflection of the resolution of their systems than about their ears. On my system the difference is not really all that subtle.
Sonos sounds best with speakers connected directly to the zp. Using the 'line out', even into a very good preamp (Audio Research sp9 mk2) and a great amp (Cary Audio Rocket 88 50 wpch triode tube) degrades the sound.
With lossles files and speakers connected directly to the zp Sonos sounds pretty good. Not quite as good as the original cd played thru a good cdtransprt/dac. Not as good as vinyl(still the best) but way better than most regular cd players and really pretty good, even for fanatics like me.
so....1) I'm going to archive into flac (unless wma-L support comes along so I can use wmp for lossless ripping) . I suspect most with high resolution systems may want to do the same.
2) Digital out is needed to fully realize the best possible sound quality.I won't buy another zp untill this feature is available.
Just my thoughts on this.