1、Durable Material: headphone amplifier made of metal shell, strong and sturdy, lasts to use, adopts anti-slip pads at the bottom for stability. 2、Portable Size: ultra-compact stereo headphone amplifier allows for easy carry around, use it anytime and anywhere. 3、Practicality: 4-channel distribution system makes up to 4 people listen to the playback with outstanding audio quality simultaneously. 4、Convenience: independent volume control enables each listener determine their own volume level via dedicated output level control knob. 5、Easy Use: 5 press buttons ensure easy control; 1/4\" and 1/8\" outputs, 1/4\", 1/8\" TRS and RCA inputs meet usage demand. Features: Durable Material: headphone amplifier made of metal shell, strong and sturdy, lasts to use, adopts anti-slip pads at the bottom for stability. Portable Size: ultra-compact stereo headphone amplifier allows for easy carry around, use it anytime and anywhere. Practicality: 4-channel distribution system makes up to 4 people listen to the playback with outstanding audio quality simultaneously. Convenience: independent volume control enables each listener determine their own volume level via dedicated output level control knob. Easy Use: 5 press buttons ensure easy control; 1/4" and 1/8" outputs, 1/4", 1/8" TRS and RCA inputs meet usage demand. POWER button--on/off, AV MUTE button--connect or cut off RCA input signal, 6.35 MUTE button--connect or cut off 6.35mm input signal, 3.5 MUTE button--connect or cut off 3.5mm input signal Specifications: Material: Metal Plug: EU Plug, US Plug(Optional) Input Impedance: 22KΩ Input Signal Level: +22dB Output Impedance: More than 16Ω Maximum Gain: 19dB/channel SNR: >98dB Input(power adapter): AC100-240V 50/60Hz Output(power adapter): 5V, 3A Item Weight: 395g / 13.93oz Item Size: 14*9.5*2.7cm / 5.51*3.74*1.06in Package Weight: 624g / 22.01oz Package Size: 24.5*13*6cm / 9.64*5.11*2.36in Note: Headphone amplifier and power adapter only, other accessories in the pictures are not included. Due to manual measurement, there may be deviation, please in kind prevail. Due to lighting or other reasons, the picture and material object may slightly differ. Packing List: 1 * Headphone Amplifier 1 * Power Adapter 1 * User Manual 1 * Headphone Amplifier 1 * Power Adapter 1 * User Manual