The KEF's get as low as 3.2 ohm and mostly around 6 ohm throughout the range. That's a no-no for bridging the Bryston according to:
http://bryston.com/BrystonSite05/pdfs/SSTAmplifiers/3B-4B-MANUAL-BRIDGED-MODE-INSERT.pdf
The 120Hz xover is suitable for passive biamping. The advantage of an active xover is removing the parasitic passive xover but, most often, that would require surgery on a PCB inside the speaker along with some deep knowledge of what you're replacing. Not recommended for a novice.
http://bryston.com/BrystonSite05/pdfs/SSTAmplifiers/3B-4B-MANUAL-BRIDGED-MODE-INSERT.pdf
The 120Hz xover is suitable for passive biamping. The advantage of an active xover is removing the parasitic passive xover but, most often, that would require surgery on a PCB inside the speaker along with some deep knowledge of what you're replacing. Not recommended for a novice.