Contact James Tanner of Bryston as he ran 3.7's with simular electronics. He will give you the scoop as to what works well with these speakers.
You can get hold of him through the Bryston web site or Audio Circle at www.audiocircle.com under the heading Audio Manufactures and scroll down to Bryston, you will find posts from James there and you can PM him. He is very truthful and honest and he won't steer you wrong.
Good luck
Fred