The interference you describe may be due to a grounding or cable shielding issue. I had this same problem, with the same sound you describe, when I had my turntable (just the motor, mind you) plugged into the one ungrounded outlet in my home (it was connected to a wall switch).
Not sure if you need to ground the Fulla or try a better USB cable (you know where to find those); my electrician told me poor shielding could cause the same issue, especially if the cable in question is near a wireless router.