Grand concepts have always fueled the muse of Who guitarist Pete Townshend. Comprehending those concepts has often eluded all but the most ardent Who fanatics. Townshend’s double-album concept for Quadrophenia has something to do with a young British mod growing up in the ‘60s, who has not merely a split-personality, but a four-way disorder (hence, QUAD). Thankfully, whether one follows this narrative thread or not, the album itself contains several of the group’s finest songs (“The Real Me,” “The Punk Meets the Godfather,” “Love Reign O’er Me”) which are so incredibly dynamic — drummer Keith Moon holds nothing back — that they continue the rewriting of the hard rock playbook the group began with Live at Leeds and solidified with Who’s Next. There isn’t a hard rock group worth hearing that didn’t learn something from the breathless screams of Roger Daltrey and the innovative power chords of Pete Townshend. Recording technology was finally catching up with their ambitions, allowing them to capture their innate savagery and raw energy without sacrifice. Quadrophenia is a modern marvel, consistently thrilling as it defines an era with innovation and ambition.