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

mitch2 thanks very much, you gave me some very good technical information here.
The problem is that i'm not going to be able to home audition all of the brands i'm considering, the list is very long :

D'agostino.
Ypsilon.
Aesthetix.
Karan Acoustics.
PS Audio.
BAT.
Modwright.

For the moment i will have the Ypsilon home demo in 2 weeks time.
The distributor is nice enough to organise a home demo for me and another client.

There is one other brand that i forgot in my list : Audionet

I had Thiel 3.7s for a couple of years. From my firsthand experience, as I have posted here before, I would only recommend a high power high current amp for 3.7s.  I had the KW 150 and it simply ran out of steam and went into clipping even at medium volumes.  I would second the recommendation of BAT 600se and 655 Se as these amps really deliver a lot of current and give good dynamics.  I also had excellent results from Marantz MA9 monoblocks and a Krell Evo 402e. Jim Thiel used to demonstrate 3.7s with the 402e if that tells you anything. 

I have never seen such excellent feedback/advice from so many on any one thread. thieliste, I think that your audition of the Ypsilon will tell you a lot.

I am totally delighted with a Classe' Audio DR-9 (100W/ch@8 ohms rated high current SS amp that doubles down to 2 ohms) with my "older" Thiel CS5is using a MW5400ES tubed player for the front end. The lower-rated-power DR-9 simply does more things right than my Krell FPB-600c at all but insane volume. May be the same with the Ypsilon vs the D'agostino or Krell in your system, dunno. Only your ears will know for sure.

Recent experience has taught me that tubes somewhere in the chain are magical with the Thiels. Makes them relax just the right amount to bring out the musicality vs analytical over-achievement without.  

As always, the synergy of the equipment chain makes the difference.
emailists' advice to leave a good amount of your budget for cables, cords, and a top power conditioner is prudent, IME.

Best to you thieliste,
Dave

dlcockrum i'm surprised you're able to drive the most difficult Thiel ever with only 100 watts even if it's doubling.
I'm sure the D'agostino classic would be a perfect match for my CS 3.7 with let's say a VAC or VTL preamp.
But who knows perhaps the Ypsilon Aelius will have enough current and sound beautiful on the 3.7s.