bigphant57Usually that means your PC has EMI issues / ground loops.
Try other USB ports, try another PC or use a wall charge, max the volume and check if the noise is gone.
If so, you should consider using optical cable and/or USB isolator like this one:
http://hifimediy.com/index.php?route=product/product&product_id=122
EDIT: Also try a different cable, preferably one with a Ferrite bead.