Upgrade Nakamichi PA 7All power amp with mono blocks

Current System:

Acoustat 1+1 speakers

Rythmik pair F12SE subwoofers

SPL Crossover (German Brand.  This separates the signal and reduces the demand on the Acoustats.  It helps bring out the mids and highs on the 1+1's

NAD C165BEE pre amplifier (plan to upgrade long term)

Technics SL-1500 C with AT 540ML cartridge in a RigB housing (think AT740ML+)

Marantz 8003 SACD (essentially retired with all CD's on digital card)

Eversolo DMP A6 streamer (occasionally use the DAC, but find it is too bright for extended listening

Schitt Bifrost 2/64 R2R DAC

Nakamichi PA 7All Power Amp (Nelson Pass Stasis design)

I am currently considering replacing the PA 7All with mono blocks, but am also willing to consider a  higher end stereo power amp.  I am looking for improved stage and instrument separation (already very good.  just want more).  I stream Amazon HD (60%), use the digital card for CD material (20%), and vinyl (20%).

These are the power amps I am currently considering:

PS Audio M 700 Mono Blocks ($3498 for pair)

Schitt Audio Tyr ($3198 for pair)

Buckeye Amps ($1550 for pair).  Worried about missing the low level Class A sound (70% of listening is done at low to mid level with 80% primarily background sound).

I would love to test these at home, but with a bad back and restocking fees I am inclined not too.  Once I get a new unit I will A/B it with the PA 7All to confirm it is an improvement.  Trying to minimize bringing too many units into the home.

I would love to hear the community's thoughts on these and potential other units to consider.  I am willing to try used, but it needs to be essentially a lock.  (I purchased the Acoustats and Nakamichi used.  Everything else was purchased new).

Thanks, Ralph