High-pass line filter to relieve main speakers from low frequency

Hi everybody
I recently purchased a subwoofer, KEF Kf92. It has a built in low-pass filter, 24 dB, that can be set from 40-140 Hz. They go with ATC SCM20sl. Their specs are: 80-20 kHz +/- 2 dB, 55-25 kHz : - 6 dB (free standing, which they are, actually: free hanging).
I wonder whether it would be beneficial to insert an high-pass filter before the power amp, consisting of a capacitor with a set point of 65 Hz. This filter might not have a huge impact because the frequency of the ATC SMC20sl rolls off quickly by itself below 80 Hz, apparently by about 12 dB/octave.
My thinking however is: the loudspeakers still receive the complete energy of the low bass from the amp. They might not be able to convert it into sound, but instead convert it into heat and distortion. So a filter will make the life of the amp and speaker easier, since at 33 Hz, only a quarter of the energy is produced.
Do you agree with me?