Oh, you're in UK. You should check out iFi iPower (5V). A really clean switching power. Someone at Computer Audiophile forum did a test between iPower vs Chinese linear power supplies. The iPower's noise level beat all LPS in the test. audiophilestyle.com/forums/topic/31119-power-supply-8-group-test-lps-and-smps/ I re-did my test again by taping up the 5V & ground contact point on Type A of USB cable and the metal exterior of both ends (type A and type B). D50 does not require 5V or ground on the USB cable to work, it doesn't care about the handshake ground etc. It just needs Data+ and Data-. It's just that the USB circuit never really powers down completely (drawing power from the external power supply), so it is always detected by the PC. All power comes from the power supply. Unplug the power supply, and I believe your hub's light would go off. Anyway, I may have heard a small difference with the 5V & ground disconnected, but too minor to confirm if it is worth it. If you're using tape, then do it (no cost involved). If you're gonna buy a special cable to disconnect the 5V+gnd... not worth it. Might as well save the money and upgrade the cable or power supply.