The RockBoard® HA 3 In-Ear Monitor Amplifier is the heart of a high-quality two-channel monitoring system for musicians. This lightweight, wired device was developed for musicians who are in a relatively fixed position on stage. It offers professional sound quality for a stereo signal or two separate monitor signals, making it perfect for use on stage or in the studio. It can be used with a belt clip or attached to any standard microphone stand using the integrated screw adapter (including reducing thread). The HA 3 can be operated with a standard 9 V battery (not included) and has a status LED that shows the remaining battery life by changing color. Changing the batteries is quick and easy thanks to the battery compartment that is easily accessible from the outside. When attached to a microphone stand, the HA3 can also be operated with a conventional 9 V DC power supply with a negative pole on the center contact (not included). The HA 3 is equipped with two combo input sockets to which both 6.35 mm TRS jack plugs and XLR jacks can be connected. Headphones or IEM systems are connected to the 3.5 mm stereo jack headphone output. The device is simply activated with the ON/OFF switch and the desired overall volume for the headphone signal is adjusted to your own needs using the volume control. Depending on the connected audio source, you can use the stereo/mono switch and the balance control to set the stereo panorama for your headphones.