rolls PM55P Personal Monitor Amp Battery Opt Built in switchable Optical Limiter. XLR Mic In & Pass Through. Ground lift on XLR signal. Stereo/Mono 1/4-in Monitor Input 3.5mm & 1/4-in Headphone outputs. Powered by one 9 volt battery or the included PS27s power supply. Lots of output level, it's loud. Belt clip is included Max Input Level: -20 dB XLR, 40 dB monitor. Input Impedance: 600 Ohm Mic, - 22k Ohm Monitor. Output Impedance: 10 Ohms. Gain: 20 dB 1/4-in, 50 dB XLR S/N Ratio: 90 db. Limit Threshold: 0 db. Current Draw: 70 Mils Nominal. Max Output Level: 100 Mil Watts @ 16 Ohm. Power: 9 - 15 VDC.