Marantz AV8003 vs Sunfire Ultimate receiver as pre

My current setup was focused on home theater but I'm finding my self listening to more music after I treated my room with absorbtion panels and supper chunks. I'm looking at adding either the Sunfire sinature (425w x 5, bryston 7B or a Mcintosh MC300 or MC350 to improve my 2 channel listening. I am leaning towards the Mcintosh amps.

I need your opinion on what to do for a pre-processor. Lets assume I purchase the MC350. How well would the ultimate receiver work as a preamp? As an alternitive the Marantz AV8003 is a bargain at $1000 used as a true preamp. What are your thoughts?

My existing 7.1 system:

B&W 801 N
HTM1
DS7
DS6
Sunfire Sig EQ 12" sub
Sunfire ultimate receiver
Arcam Alpha 8 CD
Sony S350 blueray