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
I had a similar set up as I transitioned from a receiver to separates. I used the receiver to power the center and surrounds and passed-through the L/R to an external amp. It worked fine.

However, because the Arcam and McCormack have different power and sonic signatures, you may find that the L/Rs don't integrate well with the rest of the system, ruining the surround effect. They also may not be "fast" enough during in scenes with heavy effects.

I'd suggest you uses a SPL meter to get the mains to the same levels as the rest of the system and watch a couple of your favorite movies. See if the L/R are noticeably different from the rest.
I'm afraid about the speaker sonic signature between speakers and amps not matching. This may be the price I have to pay to go this route. I will also see how the whole system sounds powered by the receiver. If I like it, I can always sell the McCormack gear.
How about a McCormack DNA HT3 and a processor of your choice? If that does not fit your budget you could use McCormack Micro Drive amps. One for the surround channels and another one can be switched to bridge mode for the center channel. Just add more Micro drives as your system expands to more surround channels. Way cool man!!!
The AVR300's amps are very good sounding. If you try the set-up as you explained above, then compare it to the AVR300's internal amps. You may find yourself selling the McCormack and using only the AVR300. I speak from experience. I thoroughly enjoy my AVR300.
I will definitley a/b the two systems...I'm hoping the Arcam sounds good as a stand alone piece, it will certainly uncomplicate the signal path...

What I really should look at is the McCormack preamp that has the dedicated theatre pass through built in...but it is costly, about 1800.
I have a similar set-up with an integrated amp with a HT pass through and a receiver driving everything else. Works extremely well - no hassle and great sound for either application.
which integrated did you buy? i believe the musical fidelty 3.5 and 5.0 have this feature.
I have the VAC Avatar Super. I have auditioned the MF-A5, which is very good.
I think this may be the simple and best sounding way to go. It will streamline my system. What price point is the VAC?

You should also consider Krell 400xi and Plinius 9200 as well as they have this feature (I did not get to audition).