A child of rock and blues who was never constrained by his roots, William “Boz” Scaggs spent half a dozen years writing great tunes and donning an assortment of musical hats. The payoff came in 1976; while other rockers were tossing grenades at disco, Scaggs cannily incorporated it into his music. The result was Silk Degrees, a witty hybrid album that went quadruple platinum (and still counting). Its first single, “Lowdown,” was a cool take on the human condition that won-of all things-Best Rhythm & Blues Song at the 19th annual Grammy Awards.