In a black shirt and pants with a white suit jacket and red pocket square, his hair upswept in a cross between a mohawk and a James Brown pompadour, JC Brooks could have stepped onto the stage of Kung Fu Necktie right out of a time machine.

But while the songs that Brooks and his four-piece band, the Uptown Sound, played Thursday drew heavily on sweat-drenched 1960s soul, it didn't have the studied feel of a revival act. Aficionados of Stax and Motown had plenty to make them groove, but so did fans of the forgotten alternative rock band Luscious Jackson, whose song "Naked Eye" turned up in the middle of the set-opening "I Can See Everything."

Brooks, who referred to himself as "a musical theater geek," threw his whole body into the songs, performing rather than simply singing them. In spite of its retro origins, "Want More," the title track from the band's new album, felt as immediate as if it had been penned in the dressing room before the show. He's got the soul singer's classic arsenal - a hoarse shout, a breathy falsetto, and a smooth croon - along with an iconoclastic attitude that's decidedly post-punk. He introduced "I Got High," an ode to his favorite form of self-medication (it involves "little green packages"), by running down a list of antidepressants he'd tried and abandoned - not something it's easy to imagine Wilson Pickett doing.

The band's breakthrough hit, which doubtless played a key role in Thursday's show being their first Philadelphia sellout, is an up-tempo cover of fellow Chicagoans Wilco's "I Am Trying to Break Your Heart," a startling reinvention that replaces Jeff Tweedy's croak with Brooks' full-throated roar.

Rather than charging into the recorded version, the band started out closer to the original before shifting gears, fulfilling Brooks' promise to go from "nice and easy" to "nice and rough." (And yes, that's Tina Turner's famous intro to "Proud Mary," delivered with only the faintest hint of a wink.) It would be easy to view their take on the song as a gimmick, a way of hitching a ride on a much better-known band's star, but they put it across with such infectious fun that it was impossible to doubt their sincerity - or, more important, to care about it one way or the other.