Tube amp for Thiel CS1.5s

First you should get a picture of the Thiel's impedance curve. If it goes all over the place, avoid using tubes.
I believe that Thiel's are VERY power hungry. Try Bryston 4B-ST or McCormack -you might be suprised! Solid state amps these days are radically good! I use ARC VT-100 Mk-I with KEF Ref 3.2's. The KEF's have a purposely flattened inpedance and work extremely well with the ARC. I had been using Audio Artistry Dvoraks with mixed results. I auditioned some BEL MK-V's (soild state) and the Dvoraks were transformed! You really have to work to achieve a great sounding system.

I have had great results using the CJ MV-55 to drive my Thiel CS2 2's. The smaller Thiels do not present a bad impedence curve to a decent 4-ohm rated tube amp. However, in a room the size of yours with the intention to use the system for home theater, the MV-55 will run out of steam if you enjoy high volume levels. But maybe your choice of the the 1.5's indicates that you do not require high volume, and if you are complementing the mains with a powered subwoofer, I would say try this combo by all means. BTW, I have found the amp to sound its best by replacing the stock Sovtek input and power tubes with, respectively, Yugoslovian EI 12AX7's, and Svetlana EL-34's (the stock 6SN7 drivers are fine).

I had concerns about driving my Thiel CS 1.5's with a tube amp but I find that my Conrad-Johnson Premier 11a does an outstanding job on these modest Thiels. They aren't the difficult load that some people make them out to be. I also find that the midrange sweetness of the CJ amp is a very good match for the slightly dry Thiels. I LOVE this combo of Thiel CS 1.5 and CJ Premier 11a. I like it even more than my previous setup that had the Classe CA-200 200w/ch amp driving the 1.5's.

Regardless of what anyone here tells you, if they have not personally tried it themselves, they don't know what they're talking about. This combo works, and it works superbly. Period, end of story.

http://mycollins.net/audio

A supporting online review by SoundStage of the Thiel CS 1.5's being driven by a modest 40watt/channel tube integrated amp.

"That said, I found that the all-tube 40Wpc Jolida SJ202A integrated amp drove the [CS 1.5] Thiels to satisfactory levels without a hitch."

http://www.soundstage.com/revequip/thiel_cs15.htm
http://mycollins.net/audio

Abecollins: You are right. Per the archived review on Stereophile's website, the 1.5's do not need tons of power but likewise will not play super loud or display extreme dynamics. If one has a small room, this should not be an issue. The review also states that the 1.5's have a very flat "resistor like" impedance (@ 4 ohms) which tube amps love. My peception (about power requirements) probably biased by the unusually small mid drivers in the later Theil designs. You're NOT going to get a huge healty sound out of a teeny (4 inch in 2.2?) midrange driver without plenty of juice!