Thank you for your purchase of the PM55P Stereo Personal Monitor Amplifi er with Limiter. This unit is a unique device for monitoring ones self and program material at the same time. It has a monitor level control and a mic level control, a mic pass-through XLR jack, headphone output jacks, and a switchable stereo/mono 1/4" monitor input jack. The PM55P is designed for performers who need to monitor their own signal, such as their vocals, with the main mix. It is very popular with drummers who need to mix a click track with a monitor signal. Church choir singers use the PM55P to monitor their voices over the musicians. And many sound technicians use the PM55P as a quick line tester to troubleshoot audio systems. The PM55P features all these benefits in a convenient battery-powered package.