Another Engine Noise Stereo problem...

So I'm back to trying to eliminate engine noise from my in boat, tower, and perfect pass beeper/speaker. Last year, I couldn't figure out the problem. I ran new grounds directly to the battery from the HU and EQ. Didn't work. I played my ipod directly to the amps, no noise. I was thinking of running power and ground directly from one of my amps to a relay and using the existing stereo power to close the relay. I would run HU, EQ, and perfect pass to the relay. Would this work? I was also thinking of re-grounding the distribution block....

Thanks!

Engine noise can be frustrating. Luckily fixing it is simple.
Put ALL grounds from ALL devices, EQ, Head Unit, Amp, Cigarette lighter if your playing from a phone or iPod that's charging, everything all to the same point. A distro block right off the battery is preferred.
The whole reason you have engine noise is because the grounds have an impedance mismatch and have to travel through other parts of the system to find a common point.
If you have done all this and it does not work, ground your head unit to your eq, ground your eq to your amps, etc. basically making a ground wire tethering all of them directly to one another's chassis.

Basically all devices in the system need to be at the same ground potential.

I had a whine from the alternator coming through my stereo and I put a GroundLoop Isolator in line behind the head unit and amp- poof gone. Cost about 20 bucks on e-bay.