Now that I've listened to the original of Death Magnetic, I can say that I understand the negative reviews about the production quality. There is definitely something wrong. This wrongness becomes salient upon listening to another CD, something that is known to have a good production. I chose Pantera's Vulgar Display of Power as a good production reference album. The difference between Vulgar Display of Power and Death Magnetic is like the difference between the sound quality of the Sony Playstation and the Sega Genesis. It is quite apparent, even to an untrained ear. Or, as an analogous example, it is like the difference between DVD and VHS.
Death Magnetic needs to be remastered or reproduced because the songs are actually very good. As I had stated, it is reminiscent of Metallica's older albums. The complaints of many reviewers is that the album suffers from clipping. I'm not sure what that is, technically, but I can tell the quality is very poor.