The PreSonus HP2 is a compact, battery-powered headphone amp that can be used on stage for in-ear monitoring or in the studio with conventional headphones. This mono/stereo amp features volume and pan knobs, an 1/8 inch. headphone input and a mini-XLR input that's available on the back. In mono mode, you can mix two channels, and the pan control can then be used to increase your own channel with an output level of 100 mV. The HP2 is especially well-suited for in-ear monitoring and gives you control over the volume of your personal monitoring signal. The HP2 also has a pan knob and mono/stereo switch alongside a volume knob that allows you to control the signal's volume. The pan knob controls the stereo or mono balance - depending on which mode you have selected. This compact device can be clipped to your guitar strap or belt, or attached to a microphone stand. Simply connect a mini XLR and a 1/8 inch. headphone jack, and you're ready to go.