<quote>I was under the impression an active pre , especially a tubed pre if well done, could add some heft, body, and dynamics to the music that would make a TVC passive sound a tad thin by comparison. The TVC's low gain (max 6db) is also a potential drawback for some systems. Which TVC did you end up getting? After this long thread, which WAS excellent, don't leave us hangin'!</quote>
Ok, here are my basic thoughts on the subject.
#1, no component is invisible, although passive units are more so (in the area of noise, for sure). After all, you're talking about a couple hundred feet of wire in a TVC.
#2, I don't know if active pres, when they're working well (synergistically, giving good results) are "adding" something or just "preventing loss". I don't know, and I don't think anybody else really knows either. You're quite right that they can give improved dynamics, body, and soundstaging, and I don't think whether it's added or it was already there means anything, because EVERYTHING we're talking about in hi-fi is ultimately artificial. What matters is the end result and how closely it mimics a live performance, to you.
#3, Active-vs-passive is system-dependent. Some source/amp combos will sound better with an active and some will not.
#4, BUT, I will say that if you have a source/amp combo that gives up nothing to an active pre with a TVC, you've got an advantage right there. You can get transparency and speed with a TVC that I don't think you can get from an active without, at least, spending quite a bit more money.
My combo of Shanling SACDP and the new Consonance Cyber 845 SET monoblocks give up more than they gain with an active pre. I even preferred a cheap resistor passive linestage to the excellent ModWright unit. This combo is as good as I've heard - fast, clear, quiet, yet harmonically dense, liquid, and projecting a huge soundstage.
The TVC, which I don't yet have, I know from prior experience will be just as transparent but is almost certain to give better dynamics.
Theoretically, I like the less-is-more approach. I like the notion of the least amount of active components. I know that adding a tube pre can give better overall sound with certain amps, but I've found that the amps I like the most don't need it.
I wanted an active pre because they're more flexible in the long haul, playing nicely with any amp and certainly never (in the case of great units like the ModWright) mucking things up in any serious way. But, in the end I decided that, for the main system, I've got the amps I want (for a long time) and they're better with a passive linestage.