Nice rig you got there! Bass is a strange phenomenon, eh? It's taken me years & years to understand & visualize how bass works. You probably wouldn't have too much of it if you'd selected a typical monitor sized speaker. The answer is the low bass vibrates your room on 3 axes: ceiling-floor, sidewall/sidewall & frontwall/backwall. So just because you aren't containing the wave fully on the frontwall doesn't necessarily mean that it will greatly affect how the wave interacts with the other 2 axes (ceiling/floor & sidewalls.) A small monitor however will tend to rely more on boundaries than a free-standing tower to generate a given amount of bass.
I'd also like to add that if you're interested in making a few improvements to your setup that you are welcome to contact me through my email as I'll require a few additional pictures of the space as well as measurements of the room's dimensions & it would be much easier to accomplish that way.
Cheers & Congrats on putting together a really great system!
