Harmonica virtuoso Little Walter was a key contributor to bluesman Muddy Waters' music through most of the 1950s. Both as a sideman and bandleader, Little Walter revolutionized the sound of blues harmonica through amplification, clasping a mike to the harp as he played. While he may not have been the first bluesman to play amplified harmonica, he explored its possibilities most fully. He was inarguably a musical genius. Little Walter could make an inexpensive, portable "mouth organ" moan and roar like a full horn section or produce an unearthly, haunting wail. Moreover, he was a tasteful and sympathetic accompanist. As journalist ...