I just hooked up an amp the other day...all im powering is (2) 6x9's and (2) 5 1/4 inch door speakers.
On my HU i have 3 sets of rca's and in my options on the HU there is a setting for SUB -10 - +10...well if i crank up that SUB setting my rear speakers get louder...does this mean i plugged my rca's into the sub out instead of the rear out? Does it really matter cuz i mean it all works. However if memory serves correct when I adjust the FADE to the rear im thinking my speakers drop out..i'll have to check that on my lunch break.
edit: i check my fader and if i adjust it all to the front speakers i still get sound out the back speakers...lol.