I had 2 10 inch memphis subs with a terrible 300 watt amp.. they all worked.. I just bought a new SPL 1500 watt amp..
I put the hot wire in, the power light came on.. Remote wire in, power light still lights up... I put the Ground wire in, and the power light goes off.
Not sure the Gauge of the wire, I got the Wiring Kit from Walmart though. I first had the ground coming directly from the battery terminal, then I tried grounding it to a spot under my backseat.
also, I tried hooking up my previous amp, and now it's not working either.
Try grounding to somewhere in the trunk. The shorter the wire, the better. Be sure its sanded down to the metal. Also make sure the wire isn't too small for the current flowing through it.