Engine Noise Help!! What else to try?
 

I need help reducing engine noise in my Nautique 2014 Sport 200. My setup: Clarion HU in the glove box, Polk 5000 amp running interiors and sub, Polk 4000 amp running 4 tower speakers, Exile Dual Zone volume controller (not powered version, just 1 knob with RCA for zone 1 and 2) located at drivers seat and RCAs run around the front of the boat nowhere near power wires. I only have 1 battery and it is located near the engine in the v-drive locker. The main power is on a Perko switch by the driver's seat.

Steps I've taken:

I cut the HU ground and rerouted it to the ground terminal on the amp (I've tried both amps). Both amp ground wires were originally grounded to the grounding terminal on the engine block. I've moved those ground wires directly to the battery terminal. The amp ground wires are running with the speakers wires, but are not near any power runs.

Does anyone have any ideas what other steps I should take?

(Note: I had noise before installing the Exile controller, but the noise is enhanced after installing it.)

I had bad engine noise and solved by switching my 4/2 channel amp from the 4 setting to 2

make sure all inputs are getting actual input.

Thanks for recommendation. Tried this, but no luck.

maybe try a ground loop insulator on the inputs?

to rule out it being an input problem, use a 3.5mm to RCA plugged directly into your speaker amp with your HU turned on

You might be able to isolate where the noise is coming from. Ignition noise is lower pitched than alternator noise. If you can find the source you can start trying to eliminate it there. Unplug the alternator and see if that gets rid of your noise.