PS Audio BHK 300 mono VS Modwright KWA 150SE mono VS D'agostino Classic stereo

Unsound,
I understand your perspective. My essential point is that listening is the final arbiter and is of course guided by personal objectives and taste. This explains why one Thiel owner will insist that high power/current SS amplifiers are the only way to go.  Another owner will retort, "been there and done that,  tube amplifier was better for me".  It appears that Thiel owners have various routes to success. 
Charles 

If i was going to go the pure wattage route i would pick the D'agostino classic amp which doubles down all the way to 2 ohms and be done with any load problems.
But since this is not my vision of things i prefer to go quality watts and a lot of refinement.
I know most older Thiels are known to work best with big older Krells and so on but this is not my cup of thea.
The CS 3.7 are not as hard to drive as the 2.4s for exemple and i'm not even talking about the CS 6 and 7.2s.
I'll let you guys know my impressions with the Aelius ll.
I don't know anyone who has tried Ypsilon with Thiel speakers yet so that's going to be interesting.
All i can say for the moment is the best i've heard to date with the CS 3.7 are the Aesthetix Atlas mono Signature + Calypso Eclipse linestage.

Thieliste,
I like your approach and priority placed on the actual listening quality, isn’t this the whole point of having home audio, to "enjoy" music reproduction?
I get the big powerful high current bipolar transistor concept to manhandle any and all speaker loads. This doesn’t mean or ensure necessarily good quality of sounnd. I really appreciate the input coupled interstage transformer and only two stages of gain design of Ypsilon, very smart! Quality watts indeed. I wish you could directly compare this amplifier to the D'Agostino on your Thiels,  two very different design concepts. 
Charles

Dealer alert but here goes: I have the BHK 300’s on my TAD CR1’S and couldn’t be happier. Ps audio planned on offering a solid state input option but the tube input just trounced it for sound quality. To me that’s a big deal since I have found hybrid seems to sound best on my system. And of course the ability to tube roll gives another level of tweak ability vs. a pure solid state design. If you ever travel to NYC and want to hear ours give me a shout out at Triodepicturesound.
Since PS audio repurposed the casework from their power products and makes things on a larger production scale, the amps are half the price or less than probably anyone else could produce them for, so you’re likely getting a $30-40k amp for the bargain price of$15k.  Why spend more?  Use the extra cash for stellar cables like the Audioquest Wel signature and Niagara 7000 power conditioner which I can attest work extremely well with these amps - yes huge mono blocks benefitting greatly in dynamics and detail  from power conditioning!  
I believe Robert Harley bought his review pair of BHK 300's.