Before electrical amplification, the guitar was easily drowned out in orchestras or noisy nightclubs. Once players were able to plug in, guitars overtook pianos and saxophones as the lead instrument in popular music. Charlie Christian bought his first Gibson in 1937 and soon became its leading exponent in jazz. As a member of Benny Goodman’s Sextet, he was also a pioneer in the desegregation of American music. Christian’s life was cut short by tuberculosis at age 25, but the four-disc Genius collects a trove of material recorded over the busy two years before his death. Prolific and influential, his licks not only shaped jazz for years to come but were echoed a decade later in country and rockabilly.