Gather round my midlife crisis

Needing some friendly advice. I recently had the front door speakers give out in my 2002 Dodge quad cab. Making a long story short, found a deal on some Polk Audio Speakers and replaced all 4 door speakers.

The truck has the Infinity sound system with the steering wheel controls. I didn't realize the factory amp only sent low frequencies to the front door speakers until I already installed them. So, here is my dilemma. I am wanting to install an aftermarket amplifier to drive my front speakers and also a subwoofer, and keeping the factory amp hooked up to the dash speakers and rear door speakers.

I've called a local car audio store and they said this should be no problem to do. However, they mentioned nothing of how to hook it up.

My question is: Can I install the aftermarket amplifier to the already existing system, without using something like the JL Cleansweep?

Thinking of using an Alpine PDX-4.100 amp (small package with required power) and a JL Audio Stealthbox. Many thanks to all who respond!!

Thanks for your input!! I found a discussion in a Polk Audio forum last week I thought you might find interesting about the Infinity factory amp for my truck. Thanks again and here ya go:

i looked in my trusty factory service manual (which since i have a 2003 also, works for his too)... and this is what i found.

its a 7 speaker system rather than a 4 speaker system -- what i mean is that the dash / front door speakers aren't on the same 'channel' -- rather, they are crossed over inside the amplifier and then the amp has 6 outputs instead of 4 ... the center speaker takes the (-) from the right channel and the (+) from the left channel and gives a mono center channel sound (weird).

the factory radio has 4 outputs to the factory amp ... + and - for front left, rear left, front right, rear right.

the amp takes the radio's high level signal and knocks it down, then it has a crossover built internal that provides about 1000 hertz to the 3.5" dash speakers at left and right (and the middle one) and below 1000 hertz to the door speakers (6x9's). the rears are full range. the amp is behind the glove box.

the amp has two harnesses going into it... just speaker inputs, 12v power, ground, speaker outs, and then the 12V remote turn on from the factory radio and a 'datalink' wire.