Eliminates ground loop hum and buzz..Leaves signal grounds connected..Passive, the unit requires no power..Converts balanced lines to unbalanced lines and vice-versa..Adjusts signal voltages to match difference in ground potential. The HE18 is a two channel audio hum and buzz remover. Everyone knows how annoying it is to have 60 cycle hum in your sound. Now you can eliminate virtually all ground hum and buzz by simply inserting the HE18 into the audio path. Plus, the unit will convert an unbalanced signal into a balanced signal, and vice-versa. This greatly improves overall noise performance.