I've had both of these pre amps for maybe 2 years now. I won't attempt to compare them too much because I've never sat down to do a direct comparison. I use my T10 at work for music, and my Vision RB at home on my living room tv. I've had a multitude of Franks gear over the years (tubes, hybrid, solid state) and I chose the Vision RB for that particular system because I wanted all solid state because we use it all day long. Movies, video games, music, television watching, and I just didn't want tubes in a system that runs a lot of hours. Also my kids use it, and Frank's stuff is bullet proof.
I feel as time has gone on (I'm a relative AVA baby, having bought my first piece in 2009) the distinction between his tube/hybrid circuits and his solid state has gotten smaller. I really enjoyed the Insight (solid state) circuit of that era on my 2nd system, but there was a certain magic/mojo going on in my FET Ultra 550 and the matching DAC that was just *fun*. When I bought the Vision RB, I was expecting a step back from the T10 but I've really been quite a fan of this preamp. It is very lively in presentation, and I'm a fan of its overall transparency and the way the high end is rendered (very detailed without being harsh). It has quite the fun factor of its own. Going between work and home, I don't really notice a drastic difference in presentation, but again, that's far from an ideal test situation.
There are a lot of folks who try to have one piece of tube gear in the chain, like you have with the T10/SET 120 pairing. I don't really see why the Vision RB wouldn't sound fantastic with the Ultravalve.
Personally I think the Vision RB is Frank's best value. It's a great preamp, its solid state so it basically will never need anything other than an available wall outlet, and it should last forever. It's a full $200 cheaper than the T10. If I were recommending a budding audiophile's budget system, I'd pick up the AVA Vision RB for 1000, the ADI-2-DAC for 1200, and the AVA SET120 you have and for about $3k you have a system that will be the equal of many far higher priced systems.
