4 channel amp wiring

Alright, I wired an amp off the rear channel of my stock head unit with a ho/low adapter for the subs. So i have the rear RCAs back in the trunk. To wire all the 4 speakers to an amp (also preferably in trunk) I would need to tap the front channel, for low RCAs, which i could do easily.. then i would have 2 sets of RCAs, front and back. do i send 4 14 or so gauge speaker cables back up to the head unit where i would tap all the individual speakers where they would normally leave the head unit, and cut the factory wire between my hi/low adapter, and where i tied in the new amplified wires. And run a pass thru the rear channel for the amplifier for the subwoofers, possibly a crossover to tune it all correctly. also, running all the speaker wires together, I wouldnt run them on the side with all the power wires, but do i need to worry about them distorting the RCA cables that are in fact giving them the signal? How do all you guys wire your four channel amps, I wish they werent door speakers, I wouldnt hesitate run the wires directly to them, but going through thouse door grommets, and all that seems to difficult when i could splice behind the factory head unit. thanks.99 Blazer LT.   Yellow Top. Big 3. Infinity Kappa Speakers All Around. Jensen CD/DVD flip out. 2 Infinity Kappa Perfect 12DVQs powered by a Alpine PDX600.1 (in one custom box, building a FG box)

It sounds like you have the right idea, although I suggest you DO NOT cut into the factory wiring harness at all.  Look up your car on the Metra Guide and purchase BOTH the "into car" and the "into radio" adapters.  This will allow you to use the factory HU and the vehicle's OEM wiring and have access to all wires without damaging your vehicle's wiring harness.  Then you can simply splice all the power, ground, etc wires together between the two adapters, and have all eight speaker wires on both sides at your disposal for LOC and for amplifier output connections.Support the12volt.com