On the Hydrogenaudio Forums I saw a reference to a command-line utility called “Declip” that purported to repair the truncated waveforms that are the hallmark of badly-mastered music.  Knowing that plenty of these exist on Rush’s Vapor Trails (mastered by Howie Weinberg), I ran Declip against it.  It didn’t get rid of all the crackling, but I think it improved the overall listening experience.  I should try to A/B the old and new to see if I can pick out the repaired version.