I have audible base to below 30 hz, just none at 40. My room is long and narrow, equipment is set up on narrow wall. 14' x 38'.
@mizike The phenomena you are dealing with is called a Standing Wave. When the bass comes out of your speakers, before you can even hear it (the ear can't hear anything until the entire waveform has passed by it), its bounced off of the wall behind you and your listening chair is positioned such that its out of phase with the incoming waveform at 40Hz.
You can do room treatment and also electronic room correction using some really sophisticated software, but you won't have much impact on the standing wave.
What room correction does is actively figure out how the room deviates from flat and equalizes it. the problem is no matter how much power you put out at 40Hz it will get cancelled, so room correction won't work.
Room treatment is the idea of installing bass traps to prevent the energy bouncing around. The problem here is that as the bass notes change, the places where the incoming and reflected wave energies combine and re-enforce (rather than cancel) changes, so unless your bass traps can move around dynamically with the music, this won't work either.
But running multiple subs does (this is the distributed bass array you've been hearing about on this thread). By running multiple subs you are able to break up the standing waves, and thus have even bass throughout the room.
People on this thread have been talking about nodes, nulls and modes- these are references to the behavior of standing waves. I'm only putting this post up so you know how these terms relate to what you are experiencing. Good Luck!