Bryston 4B-ST, Magnepan 1.6QR, suggest a preamp.

I'm resigned to the fact that my Mesa Baron Tigris integrated tube amp won't drive my Magnepan 1.6QR's to their full potential, so I'm buying a Bryston 4B-ST and need your advice on a pre-amp to match. I'd prefer tubes and could go either with or without a phono stage. I'll be using a sub, so I'd also want two pair of outputs. Suggestions?