I have a huge problem concerning my headunit and sub. I have a Sony Xplod headunit 45 watts per channel and a 12" alpine Type R sub hooked up to an MTX Thunder 502 amp. But, whenever i turn my car on and there is no music playing random sounds come out of my sub. I bought new Rockford noise free RCA cables, but it seems to still happen, the only way i can stop it is if i take the the faceplate off my headunit. It seems to get worse when my car is in park or when i shift gears.