Hattor Ultimate Power Amplifiers

It’s ignorant to clump all class D into the same basket
It could be your passive Kuzma. I had the Hattor passive, and although I loved it, I think there was an Impedance mismatch with my class D amps. Upgrading to the advanced input buffer (~$350) + shipping back to Poland. If you’re handy you might be able to order them an install yourself

Depending on your budget there’s a pair of Merrill Veritas for sale < $5K
and PS Audio M1200s with tube input stage should be available now

I have a Audio Alchemy DPA-1 + PS 5 that I replaced the Hattor with. It made a big improvement. It's for sale on AA and USAudiomart

Thanks guys. I managed to borrow a Son of Ampzilla 2 from a friend. And just coming out the gate, barely warmed up, it is clear that stepping away from the Class D monoblocks is my direction.  

By the way, I am thrilled with my Khozmo mostly passive preamp. Arek added a simple stepped  attenuator to it for me because I needed a little more gain in my system.  Arek at Khozmo was a delight to do business with also, just awesome customer service. I have had other serious preamps in my system, from Berning to Superphon,  and this Khozmo is my keeper. It is so clean and simple and it lets the music bloom. My original post was really about whether or not to go Upstream to the $3K to $5K class D amplifier level... and for now i have made my decision... A/B.

What's your budget for new amps and do they need to be Mono's?

Class D is not an optimum match for electrostatics.

middlemass and  mijostyn are correct tomflynn OP , Class-D really dislike driving 1 ohm loadings in the highs, and that is what the Martin Logan ESL’s present, and a heavy negative phase angle –68.81º at 5.9 kHz together with 4ohms loading.

Cheers George