a 2-Way Active XO allows you to Bi-amp speakers that are two way (two drivers, woofer and tweeter). Instead of a passive crossover inside the speaker cabinet, this device passes frequencies to the appropriate driver electronically.
It is usually frequency adjustable.
Of course you need 1 amp, usually a "monoblock" amp, for each driver. 4 amps for a pair of 2-way speakers.
So you probably don't need one. You no doubt have passive crossovers in your speakers. Ususally you buy specific speakers for the purpose of bi-amping them or tri-amping them.