Bad question, what is the purpose of the different groups for DVD-A? I noticed that my DVD-A can change up to 4 groups, but I did not hear anything different on the disc? Can someone educate me?

 

DIfferent groups usually (in commercial DVD-As) contain different surround modes (stereo, 5.1, etc) of the same songs. The TL defaults to the group with 5.1. Unless the songs make extensive use of the 5.1, you may not notice the difference between the stereo and 5.1 recordings that easily. Linkin Park's Reanimation for example is one DVD-A where I'm sure you'll be able to distinguish between the different surround modes.