1. 4 stereo high-power amplifier parts: up to 4 pairs of headphones and 4 volume power supplies; suitable for all types of headphones 2. High-quality sound quality: high-quality sound quality can be maintained even at the maximum volume level 3. Ultra-low noise: Provide you with excellent audio performance 4. Ultra-low noise 4580 operational amplifiers have outstanding audio performance. They are the same as the operational amplifiers equipped on full-size audio equipment. A DC 12 volt adapter is also provided. 5. Small and portable design, easy to use and carry Product name: headphone amplifier Model:HA400 Input Channels:1 Input Output Channels:4 Output Analog Inputs: 1 x Stereo Analog Outputs: 4 x Controls per Channel:Volume Form Factor: Desktop Separate volume control for each channel 1 Input with 6.3 thomann mm stereo jack Input impedance 100 Ohm 4 outputs with 6.3 mm stereo jakcs Output impedance 80 Ohm Plug Type: UK plug,it applies to Malaysia, the United Kingdom and so on. Colour:Silver Material:ABS+metal Size:103 x 6.5 x 57.2 mm Package Contents: 1 x Amplifier 1 Adapter 1 x English User Manual Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.