Linn amp and REL sub

I have two LK85's that are aktiv. I need to connect my REL sub to the bass amp and was wonder how to do this as the connectors are BFA. is it as simple as getting a pair of BFA plugs and connecting them to the REL line adn pluggintto one of the right bass outs?
If you're LK 85's are set up to be used in active configuration, they should be used with the intended speakers for the active cards. If you want, you could remove the active cards and use the amps to power your sub, and then yes, BFA's are just another type of speaker wire connectors.
extra action, did you ever connect this? with the rel sub, you have the neutrix connector that has 3 wires. check out for the instructions. 1 wire to black and 1 wire to red on the right speaker, then the yellow wire goes to the left speaker either on the red or black.