@unsound Thanks for helping me understand some of the intricacies of the CS3.5 EQ and providing some clues toward what's happening in the evolving world of Class D amplification. I agree that Bruno Putzeys has been the brain behind many of the most important advances in modern Class D electronics, so it's interesting that he hasn't yet jumped on the GaNFET bandwagon. From what I've read, it appears that most of Bruno's work continues to use MOSFETs instead of GaNFETs. We'll see if that changes in the future.
For the present, I'm generally happy with the Class D PSA M700 monoblocks powering my Thiels, but I think it's likely that newer Class D offerings will sound even better and cope with low impedance loads more effectively - even in speakers that present a less benign impedance profile than do my CS2.2s.