here are some _useful_ modes I can think of

* b-speaker mode: duplicate a stereo signal in the "surround" speakers, effectively making them into a second set of main speakers. This makes up for the lack of b outs in the 1050

* headphone processing: there's a company that makes a special gizmo for headphones which carefully alters the stereo signal so that sounds appear to come from two phantom speakers in front of the listener. This sounds more natural than the standard "music-in-my-skull" sound that headphones have. It also prevents headaches, which results from the brain trying to figure out where the hell the sound is coming from.