Hi Grunt,
My understanding of the signals for the height channels is that if there is out-of-phase ambient sound present at equal levels in both channels--like the sound of rain, or waves crashing on a beach, or a howling wind, etc--they pull that and send it to the height channels.
This may explain why if you already have effective surround channels installed (like the QS quadpolar surrounds) which will deliver a highly immersive sense of surround, it becomes very difficult to determine whether the height channels are contributing anything at all.
I ran into an acquaintance from Cnet at a Manhattan press conference and he reported that they conducted a quasi-blind listening test of the height channels turned on or off and no-one could reliably tell when they were on or off. The results were entirely random. Listeners thought they were on when in fact they were not, and vice-versa.
Regards,
Alan
