Hybrid system with separates vs. receiver

Currently I have a McCormack DNA 1 amplifier and the McCormack TLC 1 passive preamp. I am thinking about buying the Arcam Avr300 for surround sound, while keeping the McCormack for dedicated 2 channel listening. Using the preamp as a pass through, I will have the McCormack power the fronts and sub and the Arcam power up the rears and center channel. Is this a good approach? Or do you think the receiver should power the whole system? I only have one room for theatre/stereo.

Front Speakers -- Magnepan 1.6's. Room size -- 11 x 15