using a lower amperage fuse

I'm sorry to say, but the equipment your using is subject to problems. I quit using Pioneer many years ago from issues similar to this. Very odd situation, a shop installing equipment they didnt provide and then refunding the labor costs from improper gain setting. The problem is your settings + the equipment used. This equipment has a very low output and your trying to get too much out of it with bass boosts or gains or whatever. The ground shouldnt exceed 18", but probably is not the source of this issue.This is what I do for FUN!