WOW Michael, been there done that!
Years ago I used a Krell FPB 200 stereo amp with Thiel CS6's. I went through a bunch of amps and pre-amps, tube and SS. With my gear the Thiels were bright and could get down right tinny at times. Tubes took some of the brightness away. If I had to do it again I would stay away from tube pre's with 6SN7 tubes and stay with 12AX7 (the best) or 12AT7 and 12AU7's.
I never got my Thiel's dialed in to my liking and now use B&W 801s3's. Yet, I still have the 6's and use them a few days, every year or so.
I can't say how it would work with your equipment but I recently purchased a Mcintosh C2500 pre-amp. It is the best tube pre I've ever used. To my ears, it is warm and smooth. Also it reacts nicely to tube rolling.