OK, I'm playing the THX Optimizer from the Episode 1:The Phantom Menace DVD to test DD-EX. When the left surround is highlighted, sound comes out from that surround AND the rear channel, but the rear channel's volume is lower. (same thing happens for the right surround) When the rear is highlighted, sound comes from the rear, and also from both the left and right surround, but the rear is louder than the 2 surrounds. I think this is how it's supposed to work since the rear is not a discrete channel, but I'm not 100% sure that sound should be coming out from the surrounds at the same time. Sorry if this is a stupid question, I tried doing a search but couldn't find anything... Thanks.