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