Since the floors connect to the walls they re also going to shake.
Downward firing sub carpet.
The higher order harmonics when radiating direct were definitely localizing lower mid bass notes and distorting the sound stage probably due to the.
Main theater and living room but mine have a surface which is part of the sub itself example psw1200 has a down firing power port that fires to a base surface inwhich the sub.
On surfaces got me thinking at one time also.
After that the ceiling comes next.
I have a downword firing 12 inch ksw klipsch sub i now wish i had been smarter and done my homework and bought a better sub for the price anyway on the klipsch forums several posters suggested that if you have carpet like i do to put a large ceramic tile underneath the sub.
And even for a down facing subwoofer the amount of sound being absorbed by the carpet is likely going to be negligible.
A down firing subwoofer box produces a domino effect if placed inside a room.
Most down firing subwoofers are placed on softer surfaces such as carpet.
The advantages i saw to down firing was getting the woofer away from my ear the cone was about 15 away when it was direct firing.
Down firing also tends to mute any higher order issues.
And since the shaking directly affects the floor the floor starts shaking.