Mini to the max! You can use this super-compact stereo headphone amplifier with practically all headphones -four of them at the same time, to be exact! For example, you can let up to 4 different people in your studio listen to the main mix while the recording is being made, and each listener can determine his own volume level using the dedicated output level controls. The HA400 contains 4 high-power stereo amplifiers that maintain the highest sonic quality even at maximum volume levels. • 4-channel stereo headphone amplifier for use with all types of headphones • Four high-power stereo amplifiers • Output level control for each channel • DC 12-Volt adapter included