Music is usually recorded in stereo. If you want to listen in 5.1, you need to apply a DSP such as ProLogic II in the receiver.
Dialog belongs in the center channel. But, if you want it in other speakers, try applying a mode such as All Channel stereo in the receiver.
DTS is not a mode you can apply yourself. It is a data compression codec studios used to save space when putting a multichannel sound track on a disc.