It appears that the KLF 30 is actually rated at 102 db/1 watt/1 meter, and given the horn loading of its mid-range and high frequency drivers I suspect that rating is reasonably accurate.
A concern such high efficiency raises is that the noise performance of the amp that is being used becomes especially critical. The hiss levels produced by some amps which may be perfectly fine with say 90 db speakers could very well be bothersome with 102 db speakers.
FWIW I suspect that the solid state Pass XA25 I use would be fine in that regard, as it is extremely quiet with my speakers that are spec’d at 97.5 db. I have no idea, though, how its very transparent and somewhat tube-like sonic character would synergize with the sonics of the KLF 30. But in any event, before settling on an amp it would be prudent, IMO, to try to verify that others have used the particular amp successfully with comparably efficient speakers.
Good luck. Regards,
-- Al