As long as the USB cable is up to specification when it comes to shielding, I don't see how it matters. By its intrinsic qualities, a digital interconnect can have more noise since it only needs the tolerance in transmitting a serial stream of 1s and 0s. I live near a radio tower. I do pick up radio interference with various amplifier designs and analog interconnects. I found a ground loop isolator for my subwoofer that eliminates the plate amplifier getting a hum. For my main home theater receiver, I've found it has to be plugged into a surge protector or power conditioner that has a RFI filter (otherwise I'll hear the radio station in my loudspeakers). I have tried ferrite cores around analog cables, and found they do nothing (at least for RFI).