I'm trying to connect my computer to my PA and I'm getting a lot of background noise. I go from the computer's headphone jack through a 1/8" to 1/4" adaptor into either my PA or board and both sound terrible. If I listen directly from the computer to headphones, it sounds fine. I'm guessing I need the proper type of cord for the connection (this one seems cheap). If it matters, I'm using a Dell Inspiron 6000 Notebook.