Before you switch to tubes, read Srajan Ebean's article on Bel Canto's new preamp(somewhere in the Soundstage network). He found it to be a sublime match with Bel Canto amps, and this from a fairly dedicated tube guy. He also raised an interesting point about putting a relatively noisier tube preamp in a position to handle the very low-level and delicate audio signals at that point in the chain(part of the benefit of the 200.2 is the low noise and distortion level to begin with, and you run more of a risk compromising that with tubes). If it were me, I'd think twice about going with a tube preamp, and there seem to be some serious synergies with BC's new SS preamp and their digital amps. Of course you can always look at BC's own tube preamps. Best of luck.
Tim
Tim