Thank you for your input and comments!
I pose the question since I am itching to see if what is out there could improve SQ of my setup. It sounds like the consensus is both high power Pass Amp (XA60 is a no no, may be X350.5?) and Atmasphere (MA1 is good, but may be MA2 is better) should do the job very well, but unless I buy and listen to them in direct comparison to my amps (Wolcott and CJ Premier 350) driving my old non-PX panel and toroidal back plate I would not know. In my setup, both Wolcott and CJ amp can play rather loud (90+ db, I don’t listen louder 85db) without any hint of stress. Lately I put the CJ amp into more service and like it a lot, more bass than Wolcott but still exhibits transparency, warmness and full body sound.