As a Thiel dealer and 2.4 owner, I would recommend high current, high power solid state. Plinius work exceptionally well with Thiel. Simaudio works great with Thiel. I would stay away from class D, and try tube BEFORE you buy with the speakers. I am inclined to say the BAT would work nicely, but have not heard the combination. Older Krell class A designs are a great match also......
If I can help feel free to contact me.
If I can help feel free to contact me.