thats probably multichannel stereo, my personal taste is to use dolby pro logic II when listening to music, stereo is so flat and boring
, unlinke multi-channel stereo, it actually derives 5 channels from music that are entirely unique and it is capable of well mimicing a large live perfomance and giving a new perception of spatiality that i simply find incredible sounding. not to mention if you use a center channel, it removes the oh so annoying stereo sweet spot by giving a real center channel rather then an "illusion" of one.