So, new boat to me - it has a head unit, 4 speakers and a single 4 ch. 240w amp. Each time I hit the trim or tab buttons it "pops" through the speakers, can't imagine this is good for the system, not to mention irritating to me. Any thoughts as to a fix before I tear into it and search out the source. I have done systems in the past in my boats and never had this issue.

Thanks,
Mark.

for now to be safe i would unplug the amp... just so u dont blow anything when u tab up again

sounds like a ground maybe

check you ground that should be the answer

I had a problem with the engines stumbling when tabbing, turns out the batterys were bad (11.5 volts fully charged), or could be a ground issue.

its your ground wire you need to ensure that you have it grounded.. motor noises, popping, etc is all result of not being grounded typically

So, ground wire for the amp or ground wire for the entire electrical system?

just the amp and head unit but start with that amp

Cool - that is where I will start then, thanks!

ground wire from the amp. To solve the problem you may need to run a heavier ground wire from the amp to your battery. The gauge of the ground should be at least the same gauge or bigger then the power. Also make sure the ground connection is good and clean. If at all possible make sure the ground wires and the power wires aren't running next to each other this can cause noise. The power and the ground cable should be shielded.