I seem to remember in the early days of surround sound that inexpensive devices were available that generically extracted a difference signal from the front left/right channels to produce a mono surround channel without using additional amplifier power. That in fact one could just insert a speaker between the negative speaker terminals of the front channels, add a small volume device, and, voila, instant surround sound. So...would it be possible to rig up a similar installation today to extract the center rear channel of DD EX? As I understand it the same sort of phase shift technology that drove Dolby Surround is used in EX as well. Any thoughts on this? This would be a really inexpensive way to get into 6.1. After all, who doesn't have a spare speaker laying around?