The INTEGRA III SYSTEM dual audio distribution amplifier manufactured by Protech Audio is designed for use in professional applications. Typical applications would be Lecture Halls, Presentation Rooms, Conference Centers, Background Music Systems, and Library Listening Systems. The Model 899B is designed to accept two separate audio signals, and provide two outputs for each input signal. The unit is ideally suited for stereo system applications. There are two separate circuits built onto the pc assembly. Each circuit contains one bridging, transformer-isolated input, and two 600 ohm transformer isolated outputs. The inputs, and each output contain separate amplifier circuits. The gain of each input and each output amplifier, is individually adjustable, via trimpots mounted on the backplane assembly. Mounting the trimpots on the backplane assembly helps to prevent unauthorized level adjustments, and allows the gain settings to remain fixed, should a spare unit be placed into service.