Thiel Owners

@vaan whatever you choose make it 400 watts minimum at 2 imo 

^A minimum of 400 Watts into 2 Ohms is excellent advice. Depending on ones room and desired volume output, multiples of that power output into 2 Ohms could be appreciated. As far as preamplifiers go, much of it depends on the specific amplification and source components used, it’s possible that you might not even need one.

Tom, with a tri amp setup, do you hear other benefits besides better matching of the amp to the driver?
Regarding amp preferences for the 3.7, it all depends how loud you want to play and how big your room is or distance from the speakers. The 3.7 is rated at 92 dB for 1 watt and pretty efficient. The stability of an amp at 2 ohm is relevant but the need to double power from 4 to 2 ohm is only meaningful if you use the maximum output. I based this on experimenting with the bryston 7bst, which allows to switch from parallel to serial, with a minimum impedance cut in half. No difference at any level below 90 dB listening level. 

^While your point has merit consider that ;  the 92db sensitivity rating is a standard rating into 8 Ohms. Drop 3 dB for each halving of impedance from there. Now we’re looking at something that is actually closer to 86 dB sensitivity. Which is why doubling down maintains frequency linearity. Jim Thiel told me himself that the power recommendations made were for standard 8 Ohm power ratings for amplifiers capable of doubling down, and if one were to use say a tube amp one should double the power recommendations as necessary. Thiel recommended 100 Watts minimum for the 3.7’s into 8 Ohms, doubling down into 2 Ohms would bring that recommendation to 400 Watts into 2 Ohms.