Aye my memory is a little hazy on details about what the actual wires were called/how they were rated but mine usually had a beefy old fuse and ran straight off of the +'ive of the battery/extra customised rear battery.
When we set up sound off or test cars we tended to use a couple of kits like these:
Running off one/two car audio batteries that were fed off of a customised and uprated alternator
The fuse should be within 1metre (at least) of the actual battery too, and always find a safe earth
Get some EMI shielded RCA cables too and O˛ free wire as that really makes a difference
Something like this should do you ok: