The ART HP-1 is an in-line headphone amp designed for use with in-ear monitors for musicians and performers during performance and rehearsal applications. The unit offers a locking XLR-1/4" combo input and a 3.5mm output with a variable volume control knob. Connect the input to a mixer or similar audio device and connect the output to the in-ear monitors of your choice for dependable, high-quality monitoring on stage or in the studio.