SF Power 1s with Thiel CS 2.3s Enuf Pwr?

"Power 1 has only 55 Watts but it is a Tube Amp." There is a mistaken idea that tube watts are louder than ss watts. This just isn't true. Furthermore, into low impedance loads like the Thiels, the opposite is more more likely to be the case. I suggest following Thiels guidelines. In my converstaions with Jim Thiel, he suggested doubling the recommended power suggestions when using tubes.
Don't cheap out on amplification when using Thiels.

I'm not familiar with the B&K ST-180. If it is like other B&K ST models such as the ST-140, I think you'll find that these amplifiers don't really work that well with speakers that have impedance loads like the Thiels. The B&K M series are much more suitable. Still the Thiels won't deliver all they're capable of without a top quality amp with some real grunt.

3 Ohms is a tough load for a B&K ST 140.
http://www.stereophile.com/amplificationreviews/675/index9.html