94 Fiat Punto Sound System

Hi, I want to upgrade my car audio system, I have a fiat punto 94 which currently has an alpine ipod compatible face unti, stock front speakers and infinity rear speakers on the parcel shelf, my main question is how do i go about making a bassy system. I beleive that to have a good system, as my cd player has 3 pre-outs i'd need 3 amps, 1 for front, 1 for rear and 1 for subs, am i right? as if i had my rear speakers and sub(s) connected to the same pre-out the system would not be as effective? (as id have normal music coming out of the subs) Im happy woth the cd player and infinity speakers already installed and plan on spending £500 - 600 on the subs and amp. If i am right with the amp theory i would prefer to buy two, one for the rear speakers and one for the sub(s), so basically my question is am I right about the amp subject or if not can someone point me in the right direction. Thank you, Nathan.

usually a four channel amp and a dedicated sub amp is ideal. You will use the front and rear outs on the deck to the four channel amp, and the dedicated sub out to the sub amp. Of course you could use two 2 channel amps but that would be more work than necessary. Another suggestion is to invest the most amount into your front stage/speakers.