Abstract: A device for blocking high frequency noise components present in the ground circuits of digital devices from transmission to the amplification devices of an audio system comprises a conductive enclosure having input leads for connection to the positive and ground circuits of a digital device and an external output receptacle. An inductor within the enclosure is in series connection between the input ground lead and an output wire and filters the high frequency noise. An androgenous jack coupled to the ground lead couples the positive circuit and the filtered ground circuit to the amplifier.