Judicious use of the above recommendations could definitely help. If possible, also try raising them. Don’t just stuff the ports with any old thing. First try stuffing them with straws. Yes, plastic drinking straws. You will probably have to cut them. If you really want to get tweaky, experiment with different lengths to go inside the cabinet to different depths.
How to damper booming bass...
Other than turning loudness off, is there any way to lessen booming bass? Maybe stuffing up the ports in the back of the speakers? What do you think?