The problem with the 2004 5.1 mix had nothing to do with the age or elements used for the mix at all. If you listen to the 5.1 1997 mix that is on the laserdiscs you'll see that there is no problem with the mix. No reversed music rear channels, no fx coming out of the incorrect speakers, no difference in dialogue quality from shot to shot and no problems with the music being way too quiet or even missing in the mix. Lucasfilm have spouted a lot of bull as to the reasons why the mix is bad (creative decisions , my ass). The main problem with the 2004 mix is that it was handed over to Ben Burtt who put his sound FX above all other elements, but couldn't even get that right. But Lucasfilm would not admit that there was a problem with the audio mix because it would have meant a very costly replacement program.