Between 5.1 and 7.1 it's more about the room the system is setup in; in my smaller bedroom 5.1 is fine (and don't even have 7.1), in my larger room 7.1 fills in a bit better. Depends on the music, too, often I just use 2ch if that's the source. For my multich music, almost all is 5.1, but I do have some 7.1 but I do generally expand 5.1 in my larger room to 7.1, but not always. It's all a matter of preference.