hey so my factory amp has been pruned at some stage and theres no power- what has to be done to hook it up to the battery (other than running cable etc)

Your best is to run some cable your self from the battery and you will have it there for later if you wish to upgrade the amp you wont need to upgrade the power cable.

I would use 4 gauge...
expect to pay about $6m you'll need 5.5m

thanks pyroay-

i think it would have been cut from the terminals as well as in the cabin somewhere. when it stops raining ill find out where and might look at joining it at the cut in the cabin. so its just straight from amp to +/- terminals on the battery? just ive seen some funny connections loose that i thought may have been to do with it, coming from the back of the battery.

also.. do i have to use that guage wire? i have lots of 2.5mm twin and earth about and im tempted to strip that and use the active / neutral cables.

2.5mm twin and earth is most likely tps buiding cable which is definitely not suitable for automotive use as it will at best be 7 strands of reasonably thick copper which is not considered flexible enough.
Just go to jaycar or similar and get some 8ga cable it is pretty cheap.
Cheers, Outlawxr6...