Crossovers can be "parallel" or "serial". In the former the bass and treble signals are split before processing; in the latter the signal passes through some components before it is split. Almost all crossovers are "parallel" because they are far easier to design. A "serial" crossover cannot be biwired. A "parallel" crossover can be biwired, and since it is fashionable all of them offer dual binding posts. Biwiring usually improves the sound, but it is not clear why, as the only difference is splitting the signal two meters further up the wire. Could it be that biwiring is like using a thicker wire? I noticed that the more simple the crossover, the better the improvement.
