The Line Level Shifter is designed to increase or decrease signal voltage (-10dBV and +4dBu) without adding noise. It also converts back and forth between balanced (+4dBu) and unbalanced (-10dBV) signals automatically. The Line Level Shifter contains Ebtech"s Hum Eliminator technology to break ground loops that cause AC hum. The two-channel Ebtech Line Level Shifter is equipped with 1/4" ins/outs AND XLR ins/outs. It allows you to increase or decrease audio signal levels between 10dBV and +4dBu while preventing hum cause by ground loops. Passive design means no power is required. Two-year warranty.