Yeah, a subsonic filter is about not producing frequencies you don't need.
This means your amp doesn't waist power needlessly on lower frequiencies.
Although some can hear down to 16 Hz (my last hearing test put me at 18Hz to 25KHz) most people don't even hear down to 20 Hz.
SQPlus is correct, you may not hear it but you can feel it.
But know something else, what you feel can create harmonics at higher frequencies you can hear. So subsonic filters are a good means of sound deadening. No vibration, no harmonics equal no unwanted sound. That's why I set my subsonic filters around 17 to 15 Hz.