Incase if you confirmed purchasing bryston power amp, make sure you check it with your pre amp and speakers, I was a bit unhappy with a bryston pre power when i took demo with dynaudio speakers.
Couple of products to consider. I have no idea how you are going to listen to them. Both are excellent amplifiers.
At 87dB, not exactly the easiest speaker to drive but am surprised your Marantz can't make them sing.