Your last test is to pump a dvd through Dolby Digital Live and DTS Whatever (equivalent), but you fail to mention that these audio signals are either 2.1 upconverted to 5.1 DTS or DD Live, OR the signal is being entirely passed through and those two respective technologies are not doing anything at all except passing the DD EX 7.1 native signal from the Phantom Menace dvd. If you *really* wanted to test how good DD Live or DTS's equivalent is, you would take a movie file that is Prologic or Prologic IIx and spew it through your DTS or DD Live in such a way to test the actual ability of each card to transmit into a receiver for a home theater's use.
Regardless, since Phantom Menace has no DTS track, the most you did was have the computer resample a DD 5.1 track into DTS and ... if that's the case, then there's no way you could soil yourself over that when it's actually suffering quality loss for the conversion over a straight pass-through.