Don't worry, you don't need six channels of output. You can drive as many amps as you want from any RCA-cable-equipped head unit.

There are two ways you could go about it. The easiest way is to purchase amplifiers which have line-level RCA pass-through connections already built in. In that way, you could daisy-chain as many amps as you like. Or, if you didn't buy amps with pass-through connections, you could use RCA Y-adapter cables to split the channels to multiple amps.

In my installation (a 2000 Honda accord), I actually do a combination of both methods to drive multiple amplifiers. it works great.

Have fun with the installation, and good luck!

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Tony Fabris