Interesting discussion on tube pre-amps....I have an old ART TPS II stereo tube pre amp, I know, not in the same league as what you guys are talking about, but out of curiosity I fired it up today and ran the Neumann TLM 102 thru it...it made a big difference in volume and tone quality. I can only imaging what a high end pre would sound like.
This Art II has been sitting here collecting dust for a couple of years now. Somebody over at Gearslutz suggested I upgrade the tube in it. I did and the thing never worked right after that. Today I found the original tube and put it back in and it works great !! So now I have a tube pre-amp to play with, albeit a cheap one.