When a single audio signal is dived into two frequency ranges and then sent to two separate amplifiers, which in turn drive separate loudspeakers it is said to be bi-amped. A crossover network is used to divide the audio into ranges that are more suitable for the drivers that will be used to drive them. It also allows the amplifier(s) to be chosen or designed with a more specific set of criteria in mind. Bi-amping, Tri-amping, and beyond have been used in sound reinforcement systems for years and it has become quite common in active studio monitors as well.