Used a few times at the office. It shows some signs of use, but has been tested and is in working order. *Includes a three-prong power cable. This is a 4-channel headphone distribution amplifier, with independent volume control for each channel. - Model: HA 4400 - Number of channels: 4 channels - Function: Headphone distribution amplifier - Input level: -16dB - Output level: +4dBu Thank you for looking.