Erik, the
tests , blind and otherwise, run by Home Entertainment Magazine a couple years ago have been discussed here. You'll note that the difference compared with the higher-rate DD and DTS compressed tracks used in BluRay discs was essentially inaudible. This of course measures the capabilities of the formats themselves and doesn't necessarily mean that as applied on a specific disc there couldn't be an audible difference, including a difference(e.g., loudness level)which isn't due to the format.
The point is that the horrors of digital compression are grossly exaggerated in some quarters and can very closely approach audible transparency in some cases.
