Hey Pup
Actually that is the first I have heard about the QX system!
There is some good sense to it as speaking from a psycho our directional sense up front is way better than our rear directional sense particularly when there is content up front. Also contrary to what most people think we generally process audio serially and can only spot one direction at a time (in similar audio frequency bands). This is one of the rocks all us matrix guys hide under- playing the psycho acoustic shell game.
The upside of the dreaded SQ is based on solid psycho acoustics - that we are less sensitive to rear and so the SQ matrix heavily reserves its separation to the front and cludges some rear action in 3dB. I can see why it was supported at the time.
Interestingly enough the way I got into psycho acoustics is that I did a year of psychology prior to 2 engineering degrees as I was too young to gain entrance to university at the time. When my mum was house maid to the nuns, I was just on 4 years old and the nuns decided I was ready for school! No one noticed I was that young through the years because of my height but the engineering university had an age restriction so I killed year doing psychology. I later found out that my prime psych teacher, a very attractive tall Dutch blond had "thoughts" about lil ol me- the cradle snatcher!
