Low pass crossover setting & slope for Kappa 9?

I have a pair of Infinity Kappa9 speakers and need to buy a preset module for my AR EC22 crossover. I do know, that the Kappa9 spec sheet shows 80hz but that seems low for an external crossover and the specs do not show the slope speed, 12, 18 etc. I can obtain a 90hz with slope of 12 but not sure if this would be ok? I would like to know the exact setting and slope if possible. Thanks
Preamp- Audio Research SP10
Top end amp - Audio Research Classic 60
Low End Amp - Threshold S500
Speakers - Infinity Kappa 9
Crossover - Audio Research Ec 22