I'm loling at this whole thread. Such a audio noob you are...
Your components you have a high - tweeter and a mid the box you speak of is a crossover. You run one wire from the amp to the crossover and two sets of wires that go to the tweet and mid.
You'll need a distribution block to run two amps or a capacitor to split the power wire.
Get another amp and set of RCA's to run for the high side from the head unit to the amp for your (speakers) not your sub. The sub is on a low pass signal made for subwoofers. I assume you have at least two preouts on your head unit one for speakers and one for subs ?
You do not want to hookup your front speakers to your sub amp. The signal your sub amp is receiving isn't made for normal speakers. It's at a different Hz range ie LOW PASS.
I could get into this more but i'm tired. I hope this clears some things up.
