Upgrading to McIntosh Amp...?

Last week I asked my friend to bring his McIntosh 2505 (2x50watts) amp to my apartment for audition. First of, I ran my system with EAD PM 500 and EAD TM Signature. He asked me to disable sub-woofer in my system. When I disable the subwoofer and send all low frequency to Matrix 805, it's clear that no bass was found. My 805 sounded thin and dry with no bass at all. Then the magic came when we switch to McIntosh amp. I was stunned by sweet high, deep and defined bass information, and tremendous sound stage from my 805 which I never heard when pairing with PM 500. I always think that my 805 cannot produce bass at all. I've been thinking to upgrade my speaker, but now I know what's really need to be upgraded. POWER AMPLIFIER.

Let's look at my plan. I'm planning to get the McIntosh amp for my Music(85%)/HT(15%) system. Now, I'm looking at

1. McIntosh MC-7108 (8x40w): It has 8 channel but I'll either BRIDGE or BI-AMPS 2 channels for each Left, Center, and Right which uses total of 6 channels. Then uses the rest (2 channels) for surrounds.

2. McIntosh MC-162 (2x160w): This amp will drive the left and right only. I'll get a reasonable price for 3-channels amp for my center and surround speakers.

Now I need your opinion suggestion about my plans.
1. Which plan is the best move in your opinion?
2. If I decided to go for MC-7108, should I biamp or bridge 2 channels to feed my front and center speakers?
3. If I decided to go for MC-162, does any one know any good 3-channel amps that can be found used for around $300.
4. Has any one ever compare Mcintosh Amo between muti-channel series and 2-channel series? Will there be any sonic differences?

Almost forgot, these are my equipments that will be associating with the new McIntosh amp.
EAD T-7000 transport
EAD TheaterMaster Signature (Pre/Pro)
McIntosh ...................(Power Amp)
B&W Matrix 805 (L,R)
B&W Matrix HTM (center)
B&W DM602 (surrounds)

Supakit S.