Passive headphone mix. This is a passive device with an input to connect the PA or monitor amplifier and an output to connect the headphones. A volume control regulates the headphone level and internal resistors keep the unit's impedance high enough to protect the headphones. It also protects the amplifier from encountering too low a load impedance while powering tap units, the speaker system or several tap units by themselves. Dimensions: 95 x 74 x 40 mm. Weight: 317 g.