I am curious (on a basic level) how DSX creates extra channels from existing channels.
Maybe I shouldn't because I'm probably wrong, but I'd really like to take a stab at it: information that is the same in both a front channel and it's corresponding surround channel gets added to the matrixed wide channel, while information that is different is ignored. And somehow the difference in magnitude of that information between front and surround channels determines the magnitude of the information added to the wide. I wouldn't have a clue for heights unless it's a 7.1 soundtrack and uses front and surround back information.
Okay, now how does it really work?