Bi-amplifying a speaker is another way to improve sound quality, but is a more expensive option because separate amplifiers are required for the woofer and the midrange/tweeter section of each speaker. In addition, rather than using the passive crossover built into the speaker to split high and low frequencies, an electronic crossover is recommended to get the best performance. Bi-amplifying a system allows the best amplifiers to be used for the bass and midrange/treble but because of cost is used mostly for very high-end systems.