"Perhaps randomly placed midbass drivers will smooth the sound field in the midbass, up to 120Hz. It's a reasonable suggestion. Then again, your proposed configuration is relatively complex with several woofers and crossover points. I also think having multiple distant and randomly placed sound sources run up through the upper bass to lower midrange might yield another set of problems. That's getting into the audio range where vocals, piano, guitar, cello, trombone and other wind and string instruments begin."
This is simply incorrect. So that we can get our terminology straight, to me, midbass lies above 100 Hz. Everything below 100 Hz. is simply bass and there are precious few musical instruments which have fundamentals in this region.
In the modal (bass) region things like distances to the sources crossover frequencies and the like have little to no real meaning. And talking about 100 Hz (the upper limit of my multiple sub implimentation) as being "run up through the upper bass to lower midrange" is ridiculous. In the modal region the complexity of multiple subs is Exactly what one wants.