car speaker noise

I installed an aftermarket system in a 2006 Honda Accord, everything works except for this Buzzing Noise. I tried every remedy in the book but couldn't get rid of this noise. The noise only comes when the key is in the ignition position (with or without engine running doesn't matter). So, if the...

I have installed a new car audio system with one 4 channel amp and with a mono channel amp for the subwoofer. I bought everything brandnew (including high quality cables) . But I hear really annoying high frequency noise when i start the engine. How can i get rid of that noise? and what are the...