Engine noise from sub amp after new HU

I recently installed a Kenwood XXV-01D headunit to replace my old Pioneer DEH-P7000R because the buttons were falling apart and the unit died every time I flipped the face down. Anyhow, upon turning my new HU on for the first time I noticed that the audio quality wasn't nearly as clean as with the Pioneer HU: white noise-like sound can be heard at full volume with nothing playing with the Kenwood HU. Also the subs would make an extremely loud machine gun-like sound whenever they hit a low note at a good volume (which I managed to tone-down somewhat by playing with the HU's crossover settings since I figured the subs were doing this because of overlapping out-of-phase frequencies). --- Now my biggest issue is that the subs make a humming noise (noticible when nothing is playing) that only occurs when the engine is running (and it only comes from the subs). It only goes away when I turn off the engine or unplug the RCA cables. I've tried grounding the amp at a different location but there is is still noise. My conclusion is that the problem is that the HU itself is accepting engine noise and sending it through the sub preouts. Should I send the HU back to Kenwood for repairs, or would something like this solve the problem?

first of all if your power wires and your rca cables are running to thr rear together thats where your noise id coming from so try seperating them run your rca's on one side of the car and the power wire on the other side also make sure you have insolated rca cables that will help to prevent electric wave tranfer from the vehicle chasis to the rca cablesBigC

The RCA cables are running down the left side and the amp's power wire is on the right, so I don't think that's the problem (especially since I haven't moved any wires since installing the new HU, and the noise wasn't there with the old HU). I'm considering getting better RCA cables even though I've never had a problem with them with the old HU, but first I want to be certain that is the problem.

Try a ground loop isolator inline with the RCA at the H/U end.  Some H/U's have issues with rca grounding on the chassis.WOW Sight and Sound

Maroochydore

Nothing is impossible!

Do it right the first time or don't do it at all.