I am a long time ProAc owner. I'd be concerned that the Bryston (my experience is with older Bryston amps) amps might be a little on the bright side for the ProAcs. I use a Cary CAD 200 Solid State. The amp is neutral toward warm sounding and matches my ProAcs well. I tried lots of amps that were neutral to bright (in the treble). None of them were a good match for my ProAcs.
Enjoy