PreSonus HP60 Headphone AmplifierTake command of your headphone system with the HP600 Headphone Amplifier from PreSonus. The HP60 features two sets of line level, stereo inputs that are routed to all six headphones and a Mix control that sets relative levels for each headphone output. You also get an external stereo input with level control, mono, and mute for each channel so you can send each musician a feed of just their instrument or voice and separately control the levels for