Behringer MicroHD HD400 Ultra-Compact 2-Channel Hum Destroyer Removes AC hum and noise - fast, easy and reliable Breaks ground loops safely, while keeping highest sonic quality 2 independent channels for 2 mono or 1 stereo signal Automatically converts unbalanced to balanced signals without signal loss 3-Year Warranty Program* 200 Watts of powerful, high-quality sound for audiences of up to 500 people. Input impedance approximately 500 k omega, Output impedance approximately 600 omega