Features: Compact 4-channel stereo headphone amplifier Can be used for up to four headphones at the same time . for simultaneous listening of main mix with separate volume control. Comes with four stereo amplifiers that deliver outstanding performance at any volume. Clear sound with ultra low-noise 4580 operational amplifiers that are used in 19inch studio equipment. Separate volume control for each channel 1 Input with 6.3 thomann mm stereo Input impedance 100 Ohm 4 outputs with 6.3 mm stereo jakcs Output impedance 80 Ohm Dimensions (W x H x D): 103 x 46.5 x 57.2 mm Plug Type:EU Plug Voltage:DC12V Type: HA400 Headphone Amplifier color:Silver grey Material:Metal size:103 x 46.5 x 57.2 mm Package Contents: 1 x Headphone Amplifier 1 Adapter Only the above package content, other are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.