Ed Sheeran’s 2011 debut album, +, introduced the world to an unassuming pop star. Sheeran, who cut his teeth sofa-surfing and playing gigs in pubs, was a relatable everyman: His tunes combined singer-songwriter melodies with slippery hip-hop rhythms, and his lyrics were imbued with recognizable references and down-to-earth imagery. Sheeran came across as the guy you saw perform at an open mic night, and felt compelled to buy a drink for afterwards—mainly because he was that guy. Even when + began selling millions of copies, Sheeran was still showing up at gigs wearing a lumberjack shirt, loose-fitting jeans, and chunky sneakers. He was dressing for comfort; as a result, he sometimes looked like he’d wandered onto stage by accident. That approachability is maintained on x, his 2014 follow-up. But peel back Sheeran’s modest take on pop, and there’s a quietly experimental thread running through the record—best evidenced on the wanton lead single, “Sing.” Producer Pharrell Williams draws Sheeran away from his nice-guy persona, adding snapping beats, sonar-like electronics, and a grooving rhythm guitar. “I want you to be mine, lady/And to hold your body close,” Sheeran spits on the verse, sounding like a tequila-soaked playboy. Then he slides into a seductive falsetto for the chorus: “If you love me/Come on, get involved.” Such subversion is repeated on “Don’t,” which finds Sheeran taking aim at an adulterous ex-flame, and “The Man,” which is Sheeran at his most bitter. Elsewhere on x, he’s seduced by the allure of hedonism (“Bloodstream”) and forced to confront familial trauma—which he does with empowered sassiness (“Runaway”). Sheeran doesn’t abandon his duties as a swooning balladeer, of course: “Photograph” is an aching meditation on the realities of a long-distant relationship, “Tenerife Sea” is a sensuous ode to a lover, and “Thinking Out Loud” remains Sheeran’s most romantic song, forever destined to soundtrack first dances at weddings. The album’s amalgam of adventurous and innovative musicianship with crowd-pleasing reliability now feel synonymous with Sheeran’s music. But it was x that first hinted at an artist willing to test the limits of what people expected from him.