"How can you deny Pet Sounds?" asks Cheryl Pawelski, the vice president for Artists and Repertoire at Rhino Records, a major reissuer and compiler. "At some point when you're discovering music, you will get the classics. Led Zeppelin is as classic as you can get."

Steve Berkowitz, senior vice president of A&R at Sony's Legacy Recordings, says there is a huge collection of recordings to mine. "Our job is to be salespeople, marketers, and educators, in a way," he adds. "At Legacy, sometimes I think we're supposed to sell CDs; other times, I think we're a little bit of a Library of Congress and a Smithsonian."

Berkowitz steadfastly maintains that the reissues are sonically light-years ahead of the first attempts to convert analog tapes to CDs. "Nobody knew what they were doing [at first]," he says. "The first wave of CDs was to make them sound just like the albums. The engineers were not experienced. We got to a place eight or nine years ago where analog to digital got really good. Now they're able to make them sound more natural and like they were intended to sound."

The prime example of that is Kind of Blue. In the early 1990s, Sony engineers discovered that the tape machine that was used to record part of the album ran slower than standard. As a result, those songs were about a quarter note off their intended sound. So in 1992, Sony released an expanded and corrected-speed version. Then, five years later, the company released a 20- bit remastering of the disc, which it claimed would sound even better.