Sherwood Preamp # S6020cp phono stage question

This Sherwood unit has a button that says " Ultra low base EQ "
I would like to know what this button is meant to do...what is its purpose ?
Is this button for loudness or phono?
When button is in off position....the speaker woofers move back and forth.
When button is in " in" position, speaker woofers do not move.
....however they do sound better.
Thank you
This is a quote that I found describing what it does!
"A built-in Ultra Low Bass Equalizing Circuit provides a 6 db boost at 30 cycles, for subwoofer-like response on speakers that can take it. And at the same time, it rolls off the bass at 12 db per octave, effectively removing all subsonic interference."