Please keep in mind that it isn't just the recording, but the mastering, particularly in the case of recordings from the '50s through the '70s which have been remastered (on both analog and digital formats) over and over again. In particular, many recent remasters have been less about extracting better sound from the master tape than about making it sound more "modern" by adding dynamic compression. For example, the original CD releases from Dire Straits (including the "Love Over Gold" mentioned several times here) were quite good, but the touted remasters from the mid-2000s made the music a victim of the "loudness wars." And, in cases of sonically-renowned albums like DSotM, you can find websites covering dozens of different editions, and the varying sonic benefits of each.