Shadorne, I don't know how to measure it or demonstrate it, but I believe there is IMD caused by the interaction of the two speakers with each other, not the room.
As a musician I often hear beat tones and difference tones when playing with others. These same kinds of things are going on between the two speakers. I've also experience the power multiplication when a group (say five trumpeters) gets totally in sync, totally in tune and playing with equal resonance. It's hard to explain, but when you experience it it's unforgettable. Anyway, getting the speakers ideally placed within their acoustic space and relative to each other is very important, no matter what we call it.
Dave
As a musician I often hear beat tones and difference tones when playing with others. These same kinds of things are going on between the two speakers. I've also experience the power multiplication when a group (say five trumpeters) gets totally in sync, totally in tune and playing with equal resonance. It's hard to explain, but when you experience it it's unforgettable. Anyway, getting the speakers ideally placed within their acoustic space and relative to each other is very important, no matter what we call it.
Dave