stevet59, I augment the KEF Reference 1s below 80 Hz by a pair of Velodyne HGS-15s with SMS-1 acoustic room correction, I’m unaware of the subs except when they do something I know the KEFs can’t do, e.g. vibration from a low pipe organ pedal note.
As noted above, the KEFs are high-passed at 80 Hz by a passive balanced Marchand filter.
My one complaint about the Reference 1s was that large orchestrations didn’t scale as I remembered with the 107/2s, but the addition of the subs cured that. The setup can sound very large when called for, yet remain delicate for the small jazz and baroque groups I prefer.