Hull Grounding

I'm working on upgrading all of my ground connections to limit induced resistance noise and I question if new boats also have grounds from the block to the hull that need to be upgraded?

I recently ran 1/0 ground wire from the engine block to my aux stereo battery bank which also connects the ground to my main bank but I still have speaker noise while the engine runs. All stereo and amps directly terminate at one of the batteries or perko switch to limit any loops. Maybe I'm missing something?

All stereo and amps directly terminate at one of the batteries or perko switch to limit any loops.

Cant be either or, needs to be one or the other for ALL.

I'll re-route the grounds and give it another go.