George Wright's gear is great stuff, especially when paired off together as you are considering. However I'd agree with Boa2, but would stretch it a step further; neither of his SET offerings are going to offer you what I'm guessing would be a "fuller" bass than your SS setup (BTW, I'd agree to plug the amp into the wall outlet as opposed to a conditioner before you give up). Warmer? Yes. Tube Magic? Houdini would be proud! But low bass? Look elsewhere. If he is still making them, his 2A3-based push/pull Mono 10's come very close to a SET sound while giving a corresponding authority to the bass of a push/pull. They're a great combination of midrange magic with a bit more hold on the low end than any of the SET offerings George has (I've heard all of his amps - wonderful stuff...great bang for the buck too!). I've heard great things about your BC 21.1 so my instinct would be, if you do decide to swap out gear in a quest for a different, warmer sound, that you may want to hang onto that preamp and start with swapping out the SS amp. Certainly going to a thoughtfully chosen tube amp would give you a more holographic presentation, especially if you move in the direction of SET. I know absolutely nothing about your speakers so cannot comment there, but 101 db efficiency leaves the door wide open to SET power.
Good luck!
Marco
Good luck!
Marco