In 1962, a little-known Liverpool rock act called the Beatles auditioned for a recording contract with Decca Records, but were rejected on the grounds that “guitar groups were on the way out.” Besides the fact that Decca turned down the greatest rock band of all time, this anecdote has become one of the most oft-repeated in show business because of the gross musical miscalculation: five decades later, guitar groups, and guitars, are most certainly not on the way out. And countless music fans around the world harbor the ambition to play guitar…