Does that box design indicate a high pass filter below tuning point is necessary to help protect the driver? That would be where the dsp/eq in the Behringer would be better than the two Crown series of amps, and unlikely anything your avr can provide.
XLR is for an interconnect between components, not to speakers/subs (unless they're active/powered type where you're just connecting to an amp built in). Speakon is a type of connector from amp to speaker/sub
https://en.wikipedia.org/wiki/Speakon_connector....
