Why? A good many early recordings aren’t available anywhere else. “The first 25 years of the 20th century represent the birth of jazz, the blues, the Broadway musical, the big band, country music, pop singing and the Great American Songbook, not to mention a golden age of opera and a flowering of ethnic music. Superstars from the era still loom large: Enrico Caruso, Al Jolson, Bessie Smith.”