After much testing and online research, I finally found out how to not only make a 5.1 audio file, but also which of the many formats to use. Using SONY Vegas Pro 9.5 to mix 6 separate tracks to a 5.1 AC3 file. then using Audiomuxer to create a videoTS folder. then finally using common Nero 9 to burn the videoTS folder to a DVD. The resulting DVD has no video, of course, but it plays whatever AC3 files you have audiomuxer add to it in 5.1. which plays on anyone's 5.1 system. A computer can play 5.1 WAV files (and other formats), but now I can play 5.1 tunes at somebody else's house. Surround sound formats seem to be evolving in many directions. I just wanted to point other newcomers to a format that worked for me.