Subwoofer xover settings for KEF LS50W (orig model)

I hear 80 more than anything else and overlap the low and high settings because of the way the filters roll off instead of hitting a brick wall. 

Jbs,

good deal. How do you like the results? Happy with the sub as a whole? I am a big fan of subs and will probably never have a system without them. 
Do you know the slopes of the crossovers you use? 12 and 24db slopes need different overlap points. I am stuck with the single 24db for both low and high pass but it works out well for me as is. 

I'm just using the software DSP settings for the LS50W and I think they are 12db slopes but honestly not sure. I started and 80hz but to get more consistent SPLs I ended up with what I did. KEF does advocate playing with both as I did. There is a hump in the bass output of the LS50W down in that 65-75hz range in my room so this setup helped but could not eliminate that hump. 

It sounds pretty good especially once I dialed the phase in. The speakers by themselves do a much better job that I would have thought. I likely do not need a sub where I am using this but have it so wanted to experiment. It is a REL B1 so overkill for sure. I use this rig for TV 75% and music the other 25% of the time right now. The sub integration is pretty much seamless but also does not get pulled into duty too much as my main system is where I play loud music to keep the family happy. I move later this year all all this will change.

@jbs, go higher if you can. The Little woofers in the LS 50 carry the bulk of the midrange and unloading them will clean them up even further. I cross over with ESLs at 125 Hz. Try 100 Hz if you can. Roll off the LS50s a little earlier then you roll into the subwoofer say set the LS 50s to roll off at 110 Hz and set the subwoofer to 100 Hz. Also move the subwoofer so it is right against the wall between the LS50s then take the measurement from the front of the sub to your listening position and set the LS50s to exactly the same distance which should keep them off the wall a foot or two (on the radius of a circle).

The reason low crossover points are being recommended is because most sub manufacturers expect their clients to run the sub without a high pass filter on the main speakers. They are trying to bring the sub in under the main speakers. It is also much less noticeable way down and easier to integrate without screwing things up. You also have more flexibility in placement. But the improvement in distortion levels coming from the woofer more than make up for any disadvantage particularly with smaller loudspeakers that use the woofer as the principle midrange driver.
Your LS50s will grow to three times the size.