Recommendation for a highly resolving amp

The best recommendation I can think of is to stay the heck away from
your buddies home. Spectral gear with Quad 2912s? I can imagine nothing better. Sell your stuff and rent out a bedroom in his home. Maybe he needs a chauffeur?
What is his sub array?

Was it determined if the room and speakers are adjusted optimally
as suggested by Atma? Gotta start there. 

@chungjh, While not my cup of tea; I have to respect Spectral for being amongst the top of the heap for "resolution".

Benchmark told me that the AHB2 would work on my hard to drive speakers. they do work, officially in stereo mode (not officially on mono). However, working and being the very best is another matter. The AHB2 are not the best option on 2 Ohm speakers like mine.

That review of the Bryston 4B3 | Cambridge | and a single AHB2 is not an apples-to-apples comparison. A pair of AHB2 monos would have been the equivalent of the 4B3.

To me, the 4B3 does not sound as clean and fatigue free on top as the AHB2. I owned a lot of Bryston in the past, 3B-ST, 4B-SST, and  7B-SST but not the cubed line but have heard it and it has a bit of the old hardness than is not there on the AHB2.

I'm very certain the Benchmark AHB2 is the most resolving amp available... but you'll need to bridge mono them to get the same power you're getting from your Pass Labs.

Here is Dr. Mertens evaluation of the 4B3 from 2018. He is still using this pairing (which I copied) of the EAR and the 4B3 three years later in his reference system. Mainly for the resolution as a professional evaluator. I happen to agree with all his comments and using Magnepan, I can attest that fatigue is not an issue. I listen for 5 hours every night. To be fair, at the price point, the AHB2 is a fine choice. Not everyone wants to or can spend the kind of money the cubed series requires. However, if one is searching for transparency and resolution, then the Cubed amplifiers are top shelf. I’m not a fan boy, so have no interest in what the OP decides. Be happy. I know for a fact that I am....very.

https://www.fairaudio.de/test/bryston-bp17-und-bryston-4b-vor-endverstaerker-kombination/