Well first things first. if you are going to power the rear speakers, why not power the front as well? Get a 4 Channel Amp, I would go in the area of having 100X4 @ 4 ohms. Everybody has their brands, and well... I will let you decide. So from your HU, run the sub RCA to your Boss amp, then the front and rear RCA's to your 4-channel amp, I would run the front even if your not going to use it, always there if you get a 4 channel (think upgrading). Now if you get a 2 channel amp you would only need the rear RCA's left and right channels, depending on what your rear speakers are, try and find a 2 ch. amp that will give somewhere of 100X2 @ 4 ohms. Now from the HU you also have to run the blue wire, that is your remote turn on it will go to both amps. Now you have to run a Power line from your battery. I would run the minimum of 4 gauge, but you have to look at how much total wattage your looking at. It will have to have a fuse no more than 12 inchs from your battery. The Fuse amerage should match the total amount of amps that will be pulled from the amps etc. Now i would get acouple distribution blocks, makes it easier for add-ons. I would run from the blocks 8 ga. with the correct fuse. Lemme back up a second, the guy above mentioned a Capacitor, you should install that on the power line as close to the distrabution block and amp as possable. FOLLOW ALL THE DIRECTIONS that come with the amps, speakers, etc. Dont throw that little resistor that comes with the Cap. Ok back to the amplifiers... Now what you need is going to each amp are the following wires. #1 Power lead. #2 Ground #3 Remote turn on #4RCA cables appropriate channels etc. #5 the proper load for the amp i.e. speakers. I connect the Remote turn on lead first. Then I connect the Ground, then the RCA cables, and finally the Power, make sure you keep the fuses out, if you pull the one by the battery you have nothing to worry about, it takes 5 seconds. Double triple check everything. Connect the speaker wires accordingly. Turn the gain and volume all the way down on the amp(s). Now pop the fuse you pulled back in, might see a small arc. If you are installing a CAP make sure you read the directions fully. They come with everything you need, except the pair of needle nose pliars you will need to hold onto the resistor. Ok with that properly charged, its now time to listen to some MUSIC! Turn the car ON meaning running not in Aux. Now lower the volume all the way down. Slowly encrease to about mid-way, do you hear bass? Are the subs on etc? Now go to your trunk, and slowly encrease the volume and gain of the amp untill it is about what it should be for that volume. Now encrease the HU volume slowly listening for any distortion. Once you start to hear things getting ugly make a note of that Vol. setting. Now with the volume lowered you can still do some tweaking, and more tweaking at that. Take your time and just make sure your wires are all secured and if you are not able to do this in 1 day then take another day or 3 days, this isnt the easiest thing to do. Well I hope this in some way possable helped you out, if i said something wrong anyone, i apologize I am on very little sleep and watching the Patriots and Raiders game, man oh man!!!! Take it easy
