Rolls HA43 4 Output Stereo Headphone AmplifierThe HA43 is for expanding or generating four additional headphone channels. It has a 1 4" TRS stereo input, four volume controls, four headphone outputs and is powered by an included AC adapter. The unit has a 20Hz to 20kHz frequency response, small size and is very easy to use. Four stereo headphone distribution amplifier Four output level controls Small footprint makes the unit easy to use in different situations Extremely low noise