Bryston "Regular" vs "Pro"

Has anyone here auditioned any Bryston ’home’ and ’pro’ amp back-to-back to see if there is any sonic difference between the two? I’m aware of the variable gain on the ’pro’ models - that’s not what I’m asking. I was curious about anything audible, be it dynamic range, soundstage, - or any of those other adjectives we audio geeks like to use - that might distinguish one from the other.

Doesn’t matter if it’s a 2, 3, 4... base, st or sst... just wondering about any difference in the sonic characteristics.

Well, the "pro" has a potential to sound better with adjustable gain for synergy between components.
Ok, so 'potential' aside, all things being equal (using RCA inputs) would there be any detectable audible difference?
Mr "Pro" would use adjustable gain to maximize synergy to preamp and speakers. I used Bryston 3b-st and 3b-st pro, but not at the same time so can't tell, but adjustable gain of "Pro" I really liked to play with.