i would say its either alternator or earth then, i wouldnt say its power cable not unless its earthing out on something but in that case would cause you more problems then just cutting out! if theres power to the amp and the batterys fine the voltage would never change not unless the batt didnt have enough power.
as regards to eliminating the remote cable id unplug it from the amp get a tiny bit of wire and link the remote to the 12v on the amp and try that. the amp will stay on constant so dont leave it like that just see if it stops cutting out!
if these are fine and the altenator is all good wich really it should be if ure battery was a good percentage then i would start to check the amp, maybe try it in a mates car or something, and the earth.
it could also be caused by having to smaller amp wiring as if ure asking alot from the amp the amp needs alot of power and it needs to get rid of alot of power so it trys to take as much as it needs from the batt however if ure amp cabling is to small it wouldnt be able to suck enough to get it running ie: it would cut out and go into protection mode!
hope this helps
luke@awesome.audio
