The RDL EZ-HK1 Stereo Audio Hum Killer is a stereo audio transformer isolation module. It's designed specifically for use with unbalanced, high-impedance audio inputs. The device features both input and output connections on gold-plated RCA jacks. Each input jack is electrically isolated from the case itself, as well as from the output ground. Each output jack is connected to the rear-panel ground-lift switch, which is designed to eliminate hum due to ground loops. Ground loops are common when the EZ-HK1 is installed between an unbalanced audio source (such as a computer, CD player, cassette player or other consumer audio product) and the input of a grounded amplifier in an audio system.