You can use this super-compact stereo headphone amplifier with practically any headphones – four of them at the same time, to be exact! Let up to 4 different people in your studio listen to the main mix while recording, and each listener can determine their own preferred 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. Ultra low-noise 4580 operational amplifiers are employed for outstanding audio performance – these are the same op amps found in “full-size” audio equipment – plus, a dedicated 12-Volt DC adapter is included.