I have enjoyed the sound of B&K M200's and smaller Classe amps with Thiels. I think you could find both used at your price point. I suspect the Bryston 3B ST would work nicely.
Help : Need amp as improvement over Adcom 5503
I am using two channels of an Adcom 5503 3 channel amp to drive my Thiel CS2.3s. I know the impedance drops down to 2.3 ohms at certain frequencies. I wonder if this amp is really doing a good job of driving these speakers? Since I'm on a tightly restricted budget, I'm wondering what two channel amp I could get in the $700 (used) price range that would be the best improvement over the Adcom.