question about crossover settings

gajCA

So, finally got it all set up, denon x3300 with kef q300's and hsu vtf3.5.  And it does indeed sound amazing!  Question is, i set my speakers, the kefs, to small, with the crossover at 80.  Then i went onto youtube (yeah, i know) and played some bass tests at 16hz, 20hz, 25, etc, and the mains were still playing at those levels....i know they dont go down that far even without the crossover set as it was, but they were definitely playing something, and doing a lot of vibrating.  Is this normal?  I was under the impression that the frequences below 80hz just wouldnt be sent to the mains at all with the crossover settings like that.  I also did the same thing with the hsu test tones, and they were still playing.  Are the tracks playing other frequencies as well at the same time, perhaps?