Static through audio cable

Whenever I try to play music through the 3.5 mm output, i get terrible static that builds over time. It happens with most cables and happens every time with those cables, but never occurs with certain cables. I suspect the jack isn't installed correctly and is contacting the case because, if I ground the case (most of the time I set the metal back against a piece of aluminum plate I have around), the static is relieved somewhat. Has anyone had similar issues and if so, how did you resolve it?