my530i

Hi Guys,
Some of you are sound experts on this board and I have a couple of stereo rookie questions.

First of all, I have US standard sound system (10 speakers):
4 tweeters and 4 mid-range speakers are getting signals from M-ASK unit, and 2 subwoofers get signals from an amp which gets pre-amp signal from M-ASK unit.

Now my question is
If I plan to use signals coming out from M-ASK, I need to grab those signal and feed to LC to get to RCA and feed it to my new amp. From the amp to my new speakers which replace all my existing ones. Does this means that I have to disconnect signals from M-ASK to all my existing tweeters and midrange speakers? Same hold true for subwoofers? Does I-Drive complains that speakers malfunction?

I plan to use two amps: one 4-channel amp for all 4 tweeters/4 midrange (4" MB Quart), and the other amp for two subwoofers under the seat (MB Quart 8" subwoofer). I just want to fit the current speaker housing.

Your recommendation is more than welcome.

Another question is the speaker is rate 40W RMS, can I have a 75W channel from an amp to drive it? What is the guideline for this?

Thanks