Peter,
Cannot comments about CD17 as I do not have one nor have I heard one.
I do however have an rDac which I am using with a Sonos ZP90.
Previously I have tried using the Sonos digital out through my MF v-dac and neither I, nor 2 audiophile friends, could hear any difference between the Sonos internal dac and the v-dac. I like the sound of the v-dac and use it with my TV and Blu-ray player. So the Sonos internal dac is obviously pretty good. Digital interconnects used are Atlas Compass and analogue interconnects are Kimber KCAG.
Comparing the Sonos to my Leema Antila II CD player, the Sonos has a leaner and 2 dimensional sound, but you would expect this comparing it to the Sonos at 1/10th the price.
Using the rDac gives a warmer/fuller sound, this is most noticable in the mid range rather than the base, the base is not markedly different (it was OK before). The sound stage is also much improved with gaining width and depth.
Comparing the Sonos + rDac to my Antila now is much closer and I am quite amased how close given Sonos + rDav are still less than 1/4 the price. But I guess you should really add the cost of PC to rip, NAS drive, router etc. and you get closer to probably 1/2 price. Have not tried a comparison with my Chordette Gem yet - there are only so many hours in a day and I like to listen to music.
The v-dac always sounded better when using the Antila as a transport, not very close to the Antila but better than using the Sonos or Blu-ray as a source. Curiously the rDac sounds better when using the Sonos as the source rather than the Antila. I have no idea why this should be. Maybe just a lucky synergy between the components but I am glad it does..
I use a Maplin Regulated Power supply (Order Code: VN10L) in preference to the switch mode wall wart. Never even tried the rDav one having tested them on the v-dac and Gem. Don't know if its the regulated supply that improves the sound or the removal of the wall wart. Whichever, for a £17 outlay you will notice an improvement.
So my view is the rDac will improve the sound of the Sonos but I can't help with the CD17.
All of this is in context of my system which has a passive, transformer based, pre-amp (Bent Audio TAP-X) and Linn Klimax power amp into Wilson Benesch ARCs. All cables are silver. The system is revealing and detailed but not at all harsh.
At the moment I am buying lowish cost DACs, and using one per source that needs one. Am waiting for some manufacturer to wake up to the fact that I, and I assume others, do not want to go back to manually switching sources. So Chord QBD76, Bryston and Naim DACs are all ruled out.
Hope this helps, Peter
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