The THS 2 Talkback/Headphone box has a single microphone output, controlled by a latching Mic On/Off switch and a momentary Cough switch. The microphone output is a passive, straight through connection from the microphone input. This configuration ensures that the microphone will still be live on-air, even if power to the THS 2 is lost. Works with dynamic mics only. Headphone inputs consist of balanced left and right inputs on separate female XLR connectors. Separate front panel volume controls adjust the level to the left and right ears. Another balanced XLR Mono input is provided that feeds both left and right ears equally. The Mono input has it’s own volume control. Headphones with impedances ranging from 30 to 600 Ohms can be driven to full volume. Power is supplied by a 12 VAC power adapter, model # PS12AC1A, included with the unit.