Don't be fooled by the compact dimensions of this 2-channel hum eliminator, as it is an effective problem solver that should not be missing from any rack. This handy device quickly and reliably removes mains hum and interference noise. Ground loops are interrupted, and additionally, the HD400 automatically converts unbalanced signals to balanced ones. The device features two 6.3 mm stereo jack inputs and outputs for two mono or one stereo signal.