S amp provides an elegant solution for headphone monitoring, either on stage or in the studio. The S amp is a specially designed headphone amplifier that allows you to control the level balance between four sets of headphones. Providing unusually high power levels and superb audio fidelity, the S amp is compatible with virtually all popular headphone models. And just because this unit is miniature, don?t be surprised with its great sound and reliability, thanks to the use of high quality components and solid build construction. ? Four channel stereo headphone amplifiers ? Maximum output power on each channel regardless of different headphone impedances ? Four 1/4-inch stereo headphone outputs ? Individual volume control for each headphone output ? Stereo 1/4 inch input connector ? Rugged aluminum extrusion chassis ? Large rubber bumper feet ? 18 Volt AC adapter included WARRANTY 3 years parts and labor.