Hey Eric, Glass might be sick today so I'll answer your question. You will need new power wires for sure if all 3 amps are going to be installed. I'd put in 4 gauge or lower. Now when you say stock stuff, are you implying that there is power wire already in your car? If it's 4 gauge, then you should be fine. I doubt that though, cause no car company will put anything good for nothing.
I am not sure what you mean by power wire. I bought three new Stinger HP 4 gauge amp kits for the amps. Do those come with the power wire that you are referring to.
take 2 of those amp kits back dude. Buy a Distrubution block so you can hook up all power wires to that. Get some extra wire for remote and ground for the other amps. you may get a little bit of dimming on your head lights and then for that you will need a higher output alternator.
yeah power wire does come in amp kits. It's usually the thick red wire.
Don't be so quick with the returns. Remember each amp kit contains it's own 4 gauge wire and fuse. This means you can potentially power 1500W per kit. A distribution block won't allow you to have that much power cause it's dividing one power wire into several. If you don't need that much power then Fonsworth's advice is good. BTY, the power wire means the 4 gauge red wire and black/clear ground wire.