BEHRINGER POWERPLAY HA4000 Ultra-Compact 4-Channel Stereo Headphone Amplifier Ultra-compact headphone amplifier system for studio and stage applications 4 independent stereo high-power amplifier sections Highest audio quality with virtually all types of headphones even at maximum volume Phones Level control per channel DC 12 V adapter included High-quality components and exceptionally rugged construction ensure long life [Description & reviews]