can you explain why?

The battery is the largext filter capicator you can get. Why try to introduce noise into the system by grounding to the engine?

There is absolutely no reason to ground the amp to the engine. Either run each negative supply wire to the battery or create a common negative bus near the amps with a single run to the battery or main accessory negative bus.

Ground it to the battery.

Been in the electronics business for 30+ years. The battery is your best place. Use decent cable for both pos & neg.

Thanks guys.

I'm using 2/0 guage wire so it should be plenty. I'm used to car audio where the ground has to be as short as possible.

Mine is grounded to the jumper posts by the Perko switch under the rear bench.

Seems to work well and is more accessible when working on the stereo. Always disconnect the ground when working on your stereo!

Ok i stand corrected:D I was just taught years ago when I took my MECP certification that it is better to ground to the engine in a boat due to the fact that it does not flucuate as much as the ground on the battery and it offers less resitance. Don't ask me why i do not remember.

With that said i have never run into a problem grounding to the engine, and that is how i have done all the systems in boats.

I ran 0/1 gauge for power wire,used a distribution block with 4 gauge ground to battery.is this right? 1 jl 250/1 and 1 300/4

whoever told you that is an idiot don't take any more advice from them!

Agree.

The idea is to provide the lowest impedance return path possible back to the power source (the battery). Assuming your connection from the battery to the engine block is solid, either place is fine. Whichever is most convenient.