At their best, Styx combined a sweeping sense of melodrama with a grasp of meat-and-potatoes Midwestern rock. “Lady,” “Come Sail Away,” “Lorelei,” and the chart-topping “Babe” are lofty expressions of love built upon glimmering towers of sound. Augmented by Tommy Shaw’s bracing lead guitar, DeYoung brought an operatic urgency to showpieces like “Mr. Roboto” and “Renegade.”