The OWI AMP-R2SIC6 is a self-powered or self-amplified in-ceiling speaker which features a built-in amplifier on top of the speaker’s magnet. Non-amplified speakers need a separate amplifier to amplify sounds, but with self-amplified speakers you don't need a rack to hold the bulky amplifier. Another good feature of this speaker is the priority override which can accept a balanced input while suspending the input from a normal or auxiliary input. This feature is very important in times of emergency paging. It also has a built-in stereo combiner which combines two-channel stereo audio into a mono audio signal. Each amplifier can drive up to four non-amplified ceiling speakers and the amplifiers can be daisy chained up to a maximum of 10 amplified speakers. The amplifier can output 40 or 10W per speaker in a four speaker hook-up. The bass and treble controls give you maximum flexibility as far as sound quality is concerned.