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

No the 5i's are even more difficult load to drive, i'd prefer the more easier and recent 7.2s.
The problem is that 7.2s are extremely difficult to find now days on the used market but this is no hurry for me as my main speaker is the CS 3.7 anyway.

The good thing about the D'agostino Classic is that it doubles down all the way to 2 ohms, it's not the case of the other brands.

The D'Agostino shouldn't be troubled by any of those 3.
Is Gryphon an option? Or, perhaps D'agostino era Krells?

Well i did audition the Gryphon Antileon Evo but at 35K€ for a stereo amp that's very steep!
I'd prefer staying within the 25k€ range for monos or 16k€ for stereo amp.
I don't want to go the Krell route as i don't find them refined for Thiel speakers.
The Aesthetix Atlas (already auditioned) are in my short list until i demo the Ypsilon Aelius ll in 2 weeks.

Gryphon hasn't had a US presence in some time, I knew they were pricey, but just not how pricey. I can certainly understand your position. I've always like those Krells with Thiels. But, hey, it's your money.