Amp protection light

[Dannytaila]

Hi just put a sub and amp into my megane when the engine is off plays perfect but when engine is on the amp protection light comes on when turned up loud would any1 have any info to why this would happen

[marshey]

Low voltage? Overheating?

[roganp]

Could be a whole heap of things. Poor wiring, wrong gain setting, bad amp etc etc.

First question, what's the gain set at?

Second question, what brand & model amp and sub (including voice coil configuration if dual vc)