I don't think I would assume your Arcam gear won't drive the B&W's just fine. I know B&W's by reputation do their best with gobs and gobs of power driving them, but you may be very happy with the sound out of them with your Arcam.
When I first got back into the hobby I had an Arcam A-65 (40 watts). One dealer told me he would normally never recommend trying to drive B&W's with something that had only 40 watts, but because of the quality and stability of Arcam's poweramp output, he thought I shouldn't hesitate to give it a try. The problem is that you need an amp that can keep pace the B&W low ohm dip (around 2 ohms I believe) which can really tax lesser amps. I suspect your Arcam is up to this. I am not saying that more high quality power wouldn't be ideal, it just may not be necessary.