I'll tend to agree with Shandorne on the idea that IMD is what destroys the "air". I think this "etch" in the 7-12K (pick your own numbers here) is mistaken by many to initially be detail but after prolonged exposure the enjoyment just isn't there. When the etch is removed (reducing imd??) suddenly the air appears and everything relaxes. Maybe rather than "Air" i'll chose the phrase "sense of space" I like a big sound that gives me a feel for the space involved. Some people call it 3D sound others holographic and i think they all relate back to the same type of sound. This isn't a simple frequency response thing which leads me to look at the IMD as a possible culprit.
dave
dave