well, i know the reason why. dolbytone knows better. it because dvd movies support dolby digital 5.1 and dts. and when in 5.1 sound channels, the sounds kind of swallows in. makes it smaller. its have to do with noise reduction. 5.1 channels reduce a lots of noise, and it might seems easy to reduce noise but its not. only higher resolution sound makes it more possible.. i don\'t know why and what is so unique about noise reduction but dolbytone can explain i think. in order to hear sound in 2 channels, switch it when watching dvd movies or games that support 5.1 sound channels. hopefully they implement both 5.1 and 2 ch sound. so in that way, it will gives you an option to switch if you don\'t have a 5.1 receiver. but some movies might not have the 2 ch options.