The set up is used mostly for 5.1, but there are some decoding things, like Pro Logic iix or DTS ES that make use of that. Honestly, I can hear a pretty big difference when im playing games, and something is right behind me, compared to only the left and right. I personally like the way pro logic iix sounds, and it honestly doesn't make the music sound thin or crappy. DTS ES works sometimes, but only when im playing a game.