The Behringer MicroAMP HA400 is a very inexpensive, miniature 4-channel headphone amplifier. for stage or project studio use. The unit is equipped with separate operational amplifiers for each channel, and individual channel level controls.
12V DC AC Adapter
Limited 1-Year Warranty, Extendable to 3-Years with Product Registration
Behringer HA-400 - Headphone Amplifier