Krell KBX crossover.

I was doing some reading on the Krell KBX crossover and was really interested in finding one for my speakers which are B&W Matrix 800s. I am running a Krell FPB 600 with Krell B&W baf ( bass alignment filters, balanced). ARC Ref 6. Are the Krell KBX only used when bi or tri amping? Also what sonic advantages would the KBX bring to my speakers. Thanks in advance.