Ultra-compact stereo headphone amplifier for studio and stage application.With 4 headphone output channels and 1 input channel.Volume of each output channel can be controlled independently.Provides highest audio for each headphone even at maximum volume.Ultra low noise 4580 operational amplifier for outstanding audio performance.Comes with a DC 12V power adapter.Input Type: IN (AUDIO IN)Output Type: OUT (AUDIO OUT)Built-in Battery:NoRecommended Headphone Maximum Impedance:65-80 OhmType:Mini AmplifierModel Number:HA400Bluetooth:NoWIFI:NoPower Adapter:EU PlugPlug Type:EU Plug,it applies to Indonesia,,,, and so on.Item Size:.10.5 * 5.5 * 4.5cm/4.1 * 2.2 * 1.8 inchItem Weight:185g/6.5ozPackage Size:22.5 * 14 * 8.5cm/8.9 * 5.5 * 3.3 inchPackage Weight:385g/13.6ozColour:Black material:metalPackage Contents:1* amplifier1* power adapter1* English manualOnly the above package content, other are not included.Note: Light 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.