Is my listening geometry too small?

Ozfly is right. It's pretty easy to calculate the mode response of a room. The formula is on our website. You can go to http://www.rivesaudio.com/LRframes.html and click on the modes and that will show the formula. There's also a section on speaker placement and a short paper on tuning speaker placement. It is not formula based, as we have found too many variations in different forumlas with different types of speakers. We can calculate locations based on the speaker, but then we always use a variation of this method for final tuning. The method described can be used entirely for speaker placement. Another good resource is the CARA CD (we also sell it--so I am biased here). It's very helpful with speaker and listener placement and looking at where nodes and peaks of certain frequencies exist. Lastly, I would suggest that the room is part of the system. Subdoofus you do have a great system in terms of components, but the room could be 90% of the limitations (I don't know more about the room that what you've stated). The point is that the room needs to be considered as in integral part of the system. Many people don't do this and wonder why their expensive systems don't sound like they did in a dealer's showroom.

rlmm has pretty much told you what to do.

small room will almost certainly have standing waves in the corners behind the speakers and possibly in the other corners.
a cheap fix is to get a sheet of 4x8 by 1/8 th particle board ripped into 2 pieces 2'x8'x say 92" ( to fit the height of an 8' ceiling ) and stand them in the corners. this will absorb some sub 300hz waves and diffuse higher frequencies and in most instances improves clarity in room, tightening image and adding spatial ambience by removing many standing waves.

enjoy the music!

Rlmm, welcome to the forum! You are, of course, absolutely correct that tuning speaker placement is a matter of inches, not feet. Your advice is very sound and pointed out my failure to say "move it around a foot here and there and see if it makes any difference to you at all ... if not, speaker positioning may not be a driver (no pun intended) to the sound ... if so, then tune away". Again, thanks for the clarification and welcome!