Stereo Installation Question

What is the proper way to hook up an aftermarket amp and subwoofer to an aftermarket head unit? Here's what I'm thinking, but I want to make sure its right:
Pioneer 200w head unit to 4 speaker channels.
RCA pre-outs (4) from head unit to amp. (just to run the sub)
Speaker wire from amp to sub. (going to wire 2 channels to sub).
Will the pre-outs cancel the power of the head unit to the 4 regular speakers? (I hope not).

i see

It's pretty easy and frustrating at the same time-- everything you have said sounds fine--- You have your power gauge wire hooking from the battery to the amp, your ground wire from your amp to the frame of the car, your RCA's which, like you said, go from the back of your head unit to the amp-- if youre taking out the stock radio, youll have to get a wiring harness for your CD player to hook up your mids-- It takes time but if you have a good grasp on how to do it, it's a lot better. theres also a little wire thats from the back of the head unit to the amp to give it the signal wehenevr your head unit is on-- i think all in all youknow what youre doing-- if im wrong about anything, someone correct me!
-Damon

Thanks, great white.
I put in a new 200w pioneer cd player so I took out the factory one. Basically, I've replaced a lot of the factory stuff because it was outdated/underpowered. The JBL amps were just plain underpowered. I put new speaker wires in because the old ones were too thin and were choking the power. The head unit has 200w or 50/channel, and thats enough for me. I bought a 200w amp that I am going to use to power the subwoofer. If I got this correctly, I am going to run all 4 ch from the h/u to the amp with rca cables, and then bridge 2 of the channels so that I have 100w total to the sub. I just wasn't sure if I plug in the rca pre-outs that they wouldn't shut off the built in amp of the head unit. In other words, can you use both in conjunction? Normal connection to run the doors/ q panel speakers and pre-out to run a subwoofer?
Anyway, thats the plan...

O kay you're confused, or you are confusing me. Either way not too good. What you have with your head unit is basically simply explained this way: All radios, cd players and tapes decks, all produce a low level signal that is aplified by the internal amp in the radio. Some radios don't tap in to this low signal to provide rca's and some do. Just like some don't amplify, but most do. You more than likely have a radio with four low level outs (rca or pre-amped) two front and two back. You also have four high level outs (amplified) two front and two back. Most likely you also have your four high levels attached to you two door speakers and your two rear speakers. This is correct aplications for this. If you are going to run an amp off of your low level outs, you only need to run from either thr front or the rear outputs, not both. You may run both signals together and elliminate you fade abillity. If it were me I would run it from the rear so that you could fade out the sub it it was too much bass for music to music.
Either way you can use both together at the same time.
Biggin'

As previously stated, if you connect all four RCA preouts to your amps it will be ok. You will not lose signal from the head unit's amp, they are seperate. Also as stated, your amp will only need the input of 2 RCA outputs, not four. When bridged, the amp output is monoral and the subs will play.. and, if you connect only 2 RCAs, you will be able to turn the fade to the front or rear, depending on which you connect, and increase or decrease the subs. Keep in mind that the power specs of the head unit, 200 watts, are most likely peak power. Peak power is only the power the amp can deliver during a musical peak, for a fraction of a second. Regular, all the time power is almost always half of peak, in this case 100 watts. So each speaker driven off the amp in the head unit will recieve 25 watts. This is sufficient, although some 6x8s & 6x9s would benefit significantly from another seperate amp. Infinitys would be a good example.. Goodluck.

Thanks for the info guys. Very descriptive and helpful.
See, thats what I was thinking. But the guy that I talked to where I bought the amp said that you had to hook up all 4 channels or the amp wouldn't work. What I want to do is like you both said, run the 2 rear channels off the head unit pre-outs to the amp, bridge them, and then I would have the fader control to adjust accordingly. The guy at the store messed me up. It didn't make sense why you had to run 4 channels if you only are using 2 channels.