professorsvsu,
Edit: Looks like you may already be using XLRs here, so apologies for first paragraph below...
I’ve owned the A21 for ~5-yrs and I do enjoy it. I have found a significant difference in sound quality by running balanced interconnects to the amp. To my ears it sounds better...So, if you are using SE interconnects and have the means to try XLRs, it might really be worth the time/effort!! I vaguely recall reading the same, IIRC both from pro-reviewer(s) and in a forum or two...though I can’t recall which ones or I’d include any links (sorry). FWIW, the owners manual suggests XLR, too.
Sorry for ’longwind’ above, ESPECIALLY if you are already using XLRs.
I’ve also experienced aftermarket fuses altering the sound quality for less cash outlay than a new amp (I’ve only changed the external one on the A21 - though I have done it on numerous other components) - yielded improvements to my ears, but I’m not gonna try to tell you that it would be as good as a new/improved amp...but it has helped me make it through a time or two where I was weighing a component upgrade due to a lack of being "enthralled" with the sound of my music.
Regardless, I’m sure the Bryston will/would be a step up in SQ. Good luck with your quest!! I’m interested to read what you ultimately decide.
Best,
Doug