Surround sound is great in a living room or a movie theater, but why do you want it in your group exercise studio? We think you don't. Our philosophy has always been that fitness instruction is a performance, and when you go see a performance, you'll usually notice that there aren't speakers behind you and they aren't in the corners of the room. A group exercise sound system should provide forceful (some would say 'thumping') music with the voice just sitting on top.
If there are speakers in the back of the room competing with the ones at the front, speech intelligibility and the music's 'power' will usually be sacrificed. Furthermore, surround sound only really works if there is program material that is supposed to surround the listener (think a car zooming by, or a spaceship, or any number of things that exist in movie sound, but never in a fitness class).