His Japanese fans reverently dubbed Fenton Robinson "the mellow blues genius" because of his ultra-smooth vocals and jazz-inflected guitar work. But beneath the obvious subtlety resides a spark of constant regeneration -- Robinson tirelessly strives to invent something fresh and vital whenever he's near a bandstand. The soft-spoken Mississippi native got his career going in Memphis, where he'd moved at age 16. First, Rosco Gordon used him on a 1956 session for Duke that produced "Keep on Doggin'." The next year, Fenton made his own debut as a leader for the Bihari Brothers' Me...