I've enjoyed the A-1400-8, A-1400-2, 4BSST, 9BSST, and 14BSST over the last several years. Sound quality on all those amps are excellent and any one of them will extract all the resolution and nuances out of your M80s.
Yes there was a relay problem in the early Axiom amps which has been addressed in the latest versions. As for the Brystons I had a main switch repair in the 4BSST and all three Bryston amps eventually had their caps replaced. All pretty minor maintenance IMO and not worth worrying about.
Among that fine lineup of amps, I'd suggest looking for the best deal.
