A closer look at the iconic red-and-white-clad rock ‘n' roll duo reveals the depth of their raucous output. The rollicking “I'm Finding It Harder to Be a Gentleman” is elevated by sparkling keys, setting down a head-bopping groove in the process. And the nuclear guitar tones of Delta blues-indebted tracks like “Stop Breaking Down” and “Death Letter” sound like they could raise the dead.