If you have a spare cable I would swap out the one you are using now to rule out a faulty RCA cable and I would also try a cheater plug on the power cord of the EP800 to see if that solves any of the humming/drone/helicopter sounds. Other than that I dunno what else. Time to call Axiom if you have not already.

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne