Using the Behringer MA400 is easy. First, connect your microphone to the Mic In connector. You can also pass the mic signal through to other devices using the Mic Thru connector. If you encounter any ground noise, use the Ground Lift switch. Connect your monitor source to the Stereo Monitor input. Adjust the Monitor Level using the dedicated control, and choose between Mono and Stereo with the switch. Plug your headphones into either the 1/4'' or 1/8'' jack. Then just power it up with the included DC 12 V adapter. When not in use, keep it in a dry and clean place. Avoid exposing it to extreme temperatures or humidity. If it gets dirty, use a soft, dry cloth to clean it. Don't use harsh chemicals or abrasive materials as they may damage the amplifier.