I loved the sound from my 909/Cdp2 but it was bettered imo by a Rothwell passive pre - much more open and a bit less noisy. Don't forget the cdp2 also has inputs and so can be used as a good quality dac - that sonos would sound awesome. I wasn't mad on the 99 pre - no better that the cdp and fiddly buttons.... although at least it has a volume control on the front panel - you've got to use the remote with cdp2.
Its more the length of the interconnects that are an issue that the speaker cable - sounds best at a metre or less. I can heartily reccomend trying a passive - seems to bring the best out of the 909.