Dont know if this is a ground loop or not but... I have a pioneer h/u, 2 punch 800s. I recently had to change my fuse and fuse holder under the hood due to it melting together. So I replaced it and now when I turn the system on and off it has a loud popping and i can hear a high pitched noise. Then once I crank the engine it has a very loud engine noise. I have checked all grounds and all are bolted to thick metal. This only happens when i have the rcas from the head unit plugged into the amps. I can take an ipod and plug it into the amp for mids and highs and it works fine. Every thing was working fine untill i changed the Fuse holder......Any help would be great as ive been going around and around with this problem. //content.invisioncic.com/y282845/emoticons/greedy.gif.5a53e6246569d7ab79867170f3b06629.gif