Is Bass Non-Directional In A Two-Channel Rig?

When I first got my subwoofer I had it sitting directly behind my side of the couch via wireless connection. A friend of mine came over to hear the subwoofer and assumed that he was hearing the "before" since he didn't see the subwoofer. He was, however, wondering why I need a subwoofer based on what he was hearing. It's now next to the right channel speaker because the wireless connection didn't play well with my wireless printer or internet connection.

I believe that they have done studies showing that people can't pinpoint a direction below 80 Hz.

"You will increase the sound stage image size by roughly thirty percent with the proper implementation of time aligned stereo subs." - Theaudiotweak

Where does the 30% figure come from? There must be some science and math associated with such a statement.

I've always assumed that 45% of all statistics are made up on the spot, you can quote me.

Have you done that same experiment with a single sub places behind the listening position? It makes sense that that having more bass will better "fill" a room and this is what I think you're describing.

Theaudiotweak - I wasn't thinking of adding a third sub as much as wondering if you had done the same experiment with a single sub in a different location to see what people perceived about the listening stage.

I'd be interested to know if your test people that evaluated the soundstage difference would have different results using a single subwoofer. I suspect your ability to pinpoint the subwoofer is much better than even the above average Joe.

How can you be sure that the difference in soundstage results from having two stereo subs located as you have them and not just a result of any sub placed anywhere?