The Pyle PHA40 4-Channel Stereo Headphone Amplifier is a compact and lightweight stereo headphone amplifier that allows up to 4 users to listen to the same audio signal. The amp has a stereo 1/4" input jack and a set of 4 stereo 1/4" outputs. Each output has its own level control knob, letting users set their ideal volume level individually. There is a red power LED to provide visual indication that the unit is receiving power. It operates on 12 V DC power via the included power supply.