I'm using the Promitheus TVC (Ref 1) with a Eddie Vaughn customized Select. I like it a lot! The unit is not even close to broken in (only 25 hours or so on it - needs 100 - 400 hours from what I have read), but I'm liking what I am hearing. The TVC does not color nor get in the way of the music at all and does not introduce any hum or noise - it may have even lowered it a skooch - and feel I have gained a bit more bass and top-end. I like it for it's "Zen" simplicity - no tubes or power cords to worry about

It recently favored very well in a friend's system (Den) who has all Eastern Electric MiniMax gear: amp, pre, cdp, &
bba, and the Brines single-driver speakers (TL's I think). We ran the TVC in place of the EE pre first without the bba. There was a noticeable lack of gain and a drop in bass. Very non-involving and a bit boring. However, when Den reintroduced the bba, the TVC had no problem being on par with the active pre. Both of us liked what we heard and were a bit amazed how it stood up. As far as audible differences, I think it sort of tamed or rounded off the sound a bit - but in a good way. The highs weren't rolled but more like the sound was reshaped. Hard to describe. I really liked it in his system though. (Sorry, not good with all the superlatives) Folks on the
Audio Circle forum are talking about using the passive with an active and getting good synergies. Den's bba is an intriguing piece of gear.
This is my 3rd TVC as there were quality problems with the 1st two but Nicholas took care of me right away and was very accommodating. I'm also using two of Nicholas' 1.5m silver IC's. Highly recommeneded but YMMV.

Good luck!
- Ray