Subwoofer xover settings for KEF LS50W (orig model)

Yes I did search and did not see much. I figures others have done this so I'd simply ask as see if anyoen has advice. The LS50W go quite a bit lower than the regular LS50s so I'm thinking of setting the low pass xover at maybe 50hz. But I can high pass as well thru the KEFs. So I figured I'd ask here what other have done with these active speakers in terms of a low and high pass settings. Looks like KEF defaults to just a low pass 80hz which seems high. 

Also I plan to use the sub settings via the KEP app but could obviously do much of this via the REL B1 sub as well. Thx