Simple question...should be anyways, gotta ask
 

Just have been out of the "game" for a while, kinda forget how everything goes you know, if your not in it simple stuff slips away. ANYWAYS here's the simple problem, and was just looking for a quick answer. Replacing a factory stereo in a car, with a simple low end stereo, still decent quality stuff, just not extravagant. so, it's a deck, with 4 speakers. (old car) now still want some decent sound so the speakers, are bigger speakers, and an amp is required. The deck that's being used has one rca output on the back that is going to be used to run the amp. amp right now, that was bought was a 2 channel amp. I told the guy when he told me, to kick it to the curb, that he would need a 4 channel amp to do this properly, he'd still like to just get another 2 channel amp, and somehow bridge it., I said that it won't work...which I don't think it will, due to the fact that it won't be able to allow the fader to work, because the amps would be bridged, where, and this is where I'm not exactly clear....cause I don't remember.....I thought, that a 4 channel amp, had the capabilities to still run the fader....HELP! Thanx....
Any additional information will be taken as well, w/ the ideas of running the feed from the deck's amp itself, via the lines to an amp to, but I think that that will cause some sort of feed back or something. Hey, if I knew....I wouldn't be asking.:dunno:

best solution is a deck with 4 channel output and a 4 channel amp, that being said

you could use a Line Output Converter to steal the signal from the rear speakers and have two seperate amps, one of them use the output from the deck and the other use the output from the LOC, just more complicated that way

or run the speakers off of the deck since this person isn't serious about doing things right in the first place