Hi Dale,
You know, I think you can hear the location of the sub, but the improvement to the rest of the sound makes up for it.
The success at placing the bass sources, however, doesn't seem to be affected by the positon of the sub. I'm not contradicting myself, really.
I think there's some continuum between our perception of placement of deep bass (can't tell where it's coming from) and mid-range (very directional). So at 100-150Hz maybe you can tell but your brain (or mine anyways) doesn't really care nearly as much as what it gets from the higher frequencies. Instrumental music is rich in overtones, and maybe the overtones at 200-300Hz etc. will trigger your brain more than the fundamental, so even though all the bass is coming from one side the overtones will place the source wherever it belongs.
Finally, I happen to have put the sub on the right side (that's where the armoire thing is) and I think most instrumental music puts the bass instruments on the right side.
-Martin
