Your amp should power the Thiel CS 3.7 and then some with no issue. Anyway, Thiel speakers are well-built, especially their midrange and woofer drivers, however, the aluminum tweeters, on the other hand, could pose a problem if you subjected them to too much high distortion. But McCormack is known to make a well-design power amp so in a way you should be okay.
I blew one of the tweeters of my Thiel CS 3.6 speakers without even knowing it. I was using it on my HT set-up that has a Karaoke machine connected to it. I’m not sure which component was the culprit whether it was the bad movies or the bad singing that causes it or perhaps both. But in any case, the tweeters probably had enough and decided that one of them should commit harakiri. Lucky for me Thiel was still around as a company and my speaker was still under warranty they honored the warranty and send me a new one in exchange for the blown one with no charge except for the shipping.
