fun. has the sound of iridescent pop with the self-awareness, heaviness and cynicism of alt-rock or the blues. Elvis Costello and Sir Paul McCartney did it with "Veronica," as did Suzanne Vega with "Luka" and, more recently, Foster the People with "Pumped Up Kicks." The idea of wedding knarly, convoluted and disturbing lyrics to cheery, catchy hooks and melodies may be sneaky—but it's also brilliant.

fun.'s recordings are full of sweep and brio, like soccer anthems (on first listen you can't deny that although they are from New York, they would go over like gangbusters at Wembley Stadium) but with the earthbound gravity of a sincere but weathered (or rotten) heart and mind. There's no acid or bitterness in the music but the lyrics, as delivered by vocalist Nate Ruess, is another story.

Ruess has a voice more suited to Broadway theater than rock, and his near falsetto expands and soars like prime Freddie Mercury. It's a slightly off-putting voice since it has no imperfections or rough edges, and glides effortlessly like ice cubes on sheet glass, but that's half the story. Producer Jeff Bhasker (Kanye West, Adam Lambert, Drake) and bandmates Andrew Dost and Jack Antonoff take fun.'s convoluted songs and design convoluted arrangements and environments that encase them. So the smash single "We Are Young," which features Janelle Monae, isn't merely catchy but addictive; you have to listen to it over and over to absorb and appreciate the beauty and complexity of its construction.

On "Some Nights"—with its grand and layered choruses and bruising hooks—Ruess bellows "What do I stand for!!??!!!," like Nietzsche lost in his own existential self doubt and then confesses with a toddler's whimper, "most nights I don't know..." "Stars" is even better with an intro that starts as an elliptical naked ballad and then morphs into a gargantuan midtempo epic.

If Some Nights—with its theatrical arrangements, mile-deep layers of echo, swarms of swirling strings and wordy conceits—seemed to bounce off AM radio, onstage at the Riviera fun. turned its music into a full-scale opera, albeit a jolly one. By the third song of the set, "All the Pretty Girls," Ruess had flung off his shoes while bouncing, smiling and skipping about as if he was leading Romper Room.

Even on a cover of the Rolling Stones' "You Can't Always Get what you Want" he seemed supernaturally animated without a hint of anything short of joy. Granted, fun. obviously put a lot of work into its show beforehand (with one of the best-lit shows that I've ever seen in my life and a sound mix that handily conquered the Riviera's less-than-pristine acoustics) and it showed through the velocity of the show. The fact that the hetero members of fun. sponsored the Reverb Campus Consciousness Tour (which had tables and displays in the lobby and representatives from The Trevor Project, Freedom 2 Marry, and Revel and Riot) made them hard to not like. In fact, you had to work really hard to not like the band or say that its music isn't, um, fun.

If fun. seems to delight in wallowing in overcomplicated pop, acoustic troubadour Duncan Sheik thrives at the opposite extreme. When "Barely Breathing" broke in 1996, Sheik appeared as a sneakers-and-jeans-wearing innocent minus the precious ick factor of, say, a James Blunt. If Blunt made you feel like you never wanted to hear him again after "You're Beautiful," Sheik had the opposite effect. The depth of his music and the passionate and tasteful way that he recorded it put him in direct kinship with Carole King's Tapestry with the hushed intimacy of '70s-era Roberta Flack. Sheik's music is personal, alright—so personal that after his recent show at SPACE I'm convinced that he couldn't be anything but that if he tried. This, of course, doesn't make him sound like sweet baby wimp. (Are you listening, Mr. Blunt?)

The beauty and attraction of Sheik's music lie not only in his articulate song-crafting but in his rich voice, which he never pushes or stretches for effect. The emotional spaces and heady romantic conundrums in his scenarios don't need fussiness or pomp but just a direct approach. This explains how Sheik went from being a pop star to co-composing/writing a Broadway smash. That Spring Awakening conquered Broadway without getting ripped for its rock score—something that Grease (1971), Rent (1997) and American Idiot (2010) couldn't avoid—says more about Sheik's craft then the taste of New York theatrical critics.

With a new album slated for next year Sheik rolled into Space headlining the Sunset Sessions Tour and, unsurprisingly without fuss did what he does best. His cover of Depeche Mode's "Stripped" was warm and precise in a way that the original wasn't while "For You" was crystalline, elegant, and powerfully sincere. He introduced a new song, "Oh My My," as "the one you should make out to," while distinguishing another from a similarly titled song by Marvin Gaye ("It's called 'Distant Lovers' ... but mine is plural," he cracked). Tears for Fears' "Shout," presented as a duet with Laura Warshauer, came minus its buffed edge, making it less confrontational and almost languid. Spring Awakening's "I Don't Do Sadness" may have been the big ballad of the show but "Lay your Weapons Down" gave Sheik the chance to give the best performance of the night.