I have most of my music stored on an external hard disk drive. My setup is HDD - Laptop - M-Audio Mobilepre USB - Nad 3020i - Tannoy M3's. When ever I plug the HDD in to the USB it causes a displeasing static to come from the speakers. The M-Audio is also plugged in to USB port too. I have changed it around to different ports but it makes no difference. Can anyone help me out? Has anyone else had this problem.