The LEHLE DC FILTER eliminates DC voltage from analog signals. Audio signals containing DC voltage cause ugly switching noise. Now, both line and high-impedance signals are cleaned - but with no loss of sound. The DC FILTER is of full stereo type, and thus filters stereo - and, of course, mono - signals. This little aid can even process balanced signals. The LEHLE DC FILTER is a passive filter, so it needs no power supply.