"Not to pick on any specific brands, but the some of the often
recommended amps from companies such as Ayre, Bryston, Pass, PS Audio,
etc. might work wonderfully with some Thiel’s, but are not designed or
spec’d by those very manufactures, (independent testing, such as those
found in Stereophile will also confirm this) for the sub 4 Ohm loads of
some later model Thiel’s." I cannot comment on some of the other brands listed by Unsounds, but the PS audio BHK 250 amp is magnificent with my 3.7's, and i have a friend who sold a Classe amp to get the BHK for his 3.7's, and he too is very impressed and pleased. the only thing better would be to get the BHK mono blocks.