Ok so I want 2 amps, 1 4 chan for the speakers and 1 for my sub. Right now I have one set of RCA's straight to the sub amp, now if I wanted to add the other amp for all 4 speakers, I'd need 2 sets of RCA's fronts & backs, then what happens with another to the subs? since I can't add 3.

 

use y adaptors on the rear channel rca to split to the rear amp channel and the sub amp.

 

Have a look at your four channel amp, too. It might power all four speakers from just two inputs any way (this may have to be looked up in the manual).

 

Put your subs with the fronts if you have to use Y jacks....then if you want to fade out the back a bit you won't be turning the subs down....Just a tip.

 

Or invest in a dual amp balancer for the four channel. This gives you a fader for the front & rear speakers & the head unit's fader will fade between the amplifiers.

 

Great thanks guys I figured it be somethin like that.

 

It sounds from your first post like you haven't bought a 4-channel amp yet. If so, you may want to make sure that the amp you buy has a pre-amp output.

A lot of the better 4-channel amps have non-fading preamp outputs, so you can hook that up in a "daisy chain" to your subwoofer amp and still preserve fade control from your head unit.