The audio on the SD version sounds amazing as well. I just got my HD DVD player going and haven't watched too much on it yet, but so far I really can't tell a difference between DD+ and regular DD 5.1 but then again I haven't heard TrueHD and I've only watched a couple movies on it. I watched Flags Of Our Fathers which has an excellent DD 5.1 track on SD DVD, but I wasn't really wowed by the DD+ track that I heard. It wasn't by any means bad, just not THAT much better, I guess maybe I'm expecing too much, or I just need to give it more time and watch move movies.