XLR Jacks - The female XLR is used for the input connection from a microphone. The male XLR is used for the output connection to a mixing console. * The phantom DC voltage is blocked to the output to avoid the loud popping that occurs when plugging in equipment that is turned on. * Power On/Off Switch & Power/Battery Sensor LED * A fresh set of alkaline batteries will provide approximately 50 hours of continuous operation at a constant 4mA load.