How Well does Bryston work with McIntosh

I have a McIntosh C2200 preamp pushing a Bryston 4BST and it is a warm, rich, detailed and open presentation. Not sure how your combination might work, but in my experience the two brands interact synergistically. The sound and music from this combination is involving, detailed and harmonically rich.
Be sure and connect with good cables. I've had good results with Analysis Plus cables and like JPS Labs cables even better. Just a thought.

You should have no issue with this combination. As an owner of a BP-25, I find it to be a pretty neutral preamp. So, unless you have issues with the McIntosh sound signature, you should be very happy.
L