If you had working knowledge of the Pixies' and Stooges' albums, you may have been stunned by how sophisticated live sound has become since those bands disappeared the first time, and how they have adapted the advances to their own needs. And what about the best of those who never formally went away — a band like Slayer, a performer like Prince? They carry so much maturity after more than 20 years that even if they don't retain perpetual youth, they have something that might be more important: complete control over their own sound.