Amp wiring help

[SKoob]

I'm in the process of upgrading my shocking stock sound system, I've just got a pair of coax jbls in the front, these will be moved to the rear when I get some components next month, I want to amp this lot up with a 4 channel amp. I'm not keen on cutting into to loom so was going to run the speaker cable from the amp to the wiring adaptor my stereo uses and splice into that, my concern is the length is going to be a problem especially for the rears. Is there a safe length to keep within for the best results? Is there any other options without cutting the car loom? Is my plan going to be ok? I'm not going for extreme just want the best from my equipment. :fooby:

[TheGateKeeper]

RCA out from hu to amp.. Then the speaker outs from the amp to the relevant speakers simples

[SKoob]

But running to the fronts will be a ball ache lol and I'll lose the handy quick disconnect on the parcel shelf So my idea is a no goer then? Was gonna put amp under seat to reduce cable run length.

[TheGateKeeper]

My amp is under the passenger seat powering my comps. I wouldn't bother with the rears if you set the fronts up right

[SKoob]

So have you run additional wire into the doors or spliced into the existing wire?

[TheGateKeeper]

Just run some new speaker wire from the amp, under the carpet, through the rubber where the door loom goes through and into the door