ok well system has been fine for about 2 years. no dramas at all...
then on tuesday my sub blew up :( grrr
so i went and got a new one on wed and ever since then the amp power light flickers once it gets a bit of power running through it and then cuts out if i turn it up anymore...i have taken the amp fully apart and all the circuits seem fine. i have tested the power cables, fuses, earth leakage etc...all i can think it could be wouuld be the battery on the way out...
any theories???

All the circuits seem OK?
Did you check you have two power rails still?
Shorted output devices?
DC across the outputs?
Battery voltage across the amp when its turned up?

I would be going for internal amplifier issues.

is the rating of the sub the same as the amp? (resistance etc?)

my amp was doin the same thing, its completly dead now tho, apparently the main audio control thing in it had burnt out.

cheers guys...will chuck it into my brothers car and see what happens in there...
if not new sub and amp in a week...grrrrr