I've read recently that the omnidrectional nature of bass is not quite correct and has been repeated so many times since 1964 that it has been accepted as gospel. From what I remember offhand the original study noted that MOST people (blind study by the way) could not sense/hear the direction of low bass but the percentage of people who could increased as the frequency increased above 70hz.

I also run sound through two subs right under the mains but cannot understand (or did I miss it above) why no one really discussed phase problems which can occur when you split the bass signal to two subs--you can have some notes (depending on distance/position of the subs I believe) cancel one another out (except perhaps for some harmonics). Luckily my subs have a phase switch so when I'm watching movies with the combined .1 LFE I can flip the phase switch on one of the subs and double the LF impact in many scenes.

I don't pretend to be and expert and a little knowledge can be a dangerous thing but I think this is an issue that you're missing in this discussion. Soundhound mentioned phase issues monitored in the recording process but that wouldn't do anything for identical sounds played by two subs which cancel each other out because they may be out of phase (or is it in phase? I think out) due to their position.

Anyway, I just wanted to hear some feedback from folks who know more than me.