I now have 2 very good options to power the Thiel CS3.7. Both do not publish specs for 2 Ohm operation but I spoke with the designer of each amp and they said they both have a lot of power at 2 Ohms.
I was using a single Benchmark AHB2 with a ROON convolution file that dropped my output my 10dB. So I was using close to 80% of the volume to get around 65-70db. A strain on the amp.
I now have 2 AHB2 in mono that are capable to 2 Ohm with an unpublished spec. The sound is great, a lot bigger, harder hitting, and engaging than with the single AHB2.
the volume control is also set to about to about 50% for 65-70dB via the convolution. This is a home run. Cost is $6K for both brand new.
I also got the CODA CSiB integrated the other day mainly for my RAAL SR1a headphones but I wanted to see how extra power translates with the Thiel CS3.7. In terms of the comparing it to a single AHB2 it is also was harder hitting, bigger, and engaging. I was getting totally into the music. The CODA however was not as crystal clear as the AHB2. Some may prefer that. I like the AHB2's presentation a little more because of the clarity. I guess that clarity is expressed by some softness to the sound on top. The details are there but it is not as sharply defined as the AHB2.
The CODA was in 10/10 condition, was a used unit, built in 2018, and cost $3.4K. So these are 2 really great options to power the Thiel CS3.7. Do not let the low price dissuade you from checking them out.