The INTEGRA III SYSTEM Audio Distribution Amplifier modules are designed for professional audio applications. These units are intended for high reliability, 24/7 applications. There are eight audio distribution amplifier modules. Choices to be made are microphone level input (4 models) or line level input (4 models), and number of outputs (2 to 5 per module). The gain adjusting trimpots are mounted on the backplane assembly. Trimpots mounted on the backplane allow the gain adjustments to remain set, even when a spare unit is put into service Model numbers with 2 to 4 outputs may be linked. The link feature allows the units to be connected together to provide additional outputs from one input section. By offering different models, the system designer can choose a unit that will fit the application perfectly. This will result in a more cost effective design. Also, the distribution amplifiers can be mixed and matched with other INTEGRA III SYSTEM cards, such as mixers and remote controls, within the same card frame. The input section on the microphone input models, is low impedance (150 ohm) balanced, transformerisolated. An on-board, push-on jumper supplies 15 volt phantom power, for condenser microphones. The input section on the line input models is bridging (10 kohm) balanced, transformer-isolated. The gain of the input section is adjustable via a trimpot.