The ST-300 base transmitter features 17 user selectable frequencies controlled by a front mounted control buttons and LCD display, a headphone jack with adjustable level for input signal monitoring, and a peak reading on the LCD display for visual input monitoring. On the back of the unit is a balanced XLR-3F with selectable mic, line and 70 volt input options, as well as an unbalanced 1/4-inch input. The input selection and attenuation is all done from the controls on the front panel, no special tweaker required.