A speaker or PA management system is a signal processor, connected between the mixer and the amplifiers of a PA system, that combines the features of many of the processors previously discussed all in one box, in order to keep the final mix sounding good and the speakers safe from damage. These features include compression, limiting, and equalization all dedicated to matching the music to a venue. A PA management device could also provide the crossover and signal-routing function for a large multi-speaker PA system.
Some PA management devices include automatic feedback suppression, which senses whenever a note starts to ring out that way and turns it down. A very handy feature to look for is a built-in RTA (real time analyzer) and auto-EQ to measure and automatically adjust your system's frequency response to attain the best-sounding curve possible, even if it plays in a different room every night. If the venue is large, you may want to think about including a time alignment/delay feature, so speakers in the rear can be coordinated with the front speakers and sound clear, not echo-y.