Inject 5 volts of clean power clean via the ‘separate’ micro port. This disconnects the USB power from the PC and replaces it with clean external power. For ultra-low noise, use our 5-volt iPower X.
Adding the separate 5 volts to the unit is necessary to ‘break’ the earth/ground on USB-powered DACs. This is not required for DACs with an internally-powered USB section.