There's a company from Sweden that manufacturers Supra Cables that you can find on Ebay. I took a chance and bought a 1 meter USB for $50. I didn't know how much HF noise I was dealing with until I installed this cable. iFi has a new USB gadget called the iSilencer+. Looks kinda like a Jitterbug. That Supra USB has a more beneficial effect than the iFi. That's their website but they don't sell anything. They do explain why their cables work. Hope I didn't commit a fau pax.
http://www.jenving.com/
http://www.jenving.com/