Audio Systems: 2003 Dodge Stratus Factory amp, speaker sound system, infinity sound

Question
I have a 2003 Dodge Stratus Coupe R/T with the premium 7-speaker Infinity sound system.  I replaced the factory stereo unit last year with one of my own.  Now recently I got a sub and amp installed.  Since the 7-speaker sound system is run off of the factory amp, by adding my sub's amp I am now running two amps from my stereo.  If I turn the stereo's volume level up to about 15, the 7 speakers are pretty much maxed out, any louder and theres distortion and they will be damaged.  The problem is, at volume level 15 the sub's amp isn't being told to play loud enough, I would need to turn it up to at least 25.  I've already turned the gain on the sub's amp all the way up, what I'm looking for is possibly a way to turn the gain the 7-speaker's amp down or something like that, that way they would be playing at a lower level and I could turn the volume up louder.  Do you know any way to change anything like that on the factory amp in my car?  Or do you have any specs or information on the amp at all?  I've searched all over and can't find anything about it.  Or as a second question, do you have any other ideas on how to fix my problem?  Thank you for any help.

BJ

Answer
Hello BJ,
You will need the wiring diagram of the vehicle to do this.
To lower the level of the input to the Factory amp, on some the gain is adjustable with a small adjustment pot. If not then you will need to install gain dropping resistors across the input to the amp, one resistor for each channel. You will need to do a trial and error to find the value of the resistors that will give you the best overall output matching to your second amp.

TOM,
T&D
tdeser@zoominternet.net