Since turning irony-minded heads in 2002 with its debut single "Losing My Edge," LCD Soundsystem has made a name for itself as the leading purveyor of winking dance tracks. With big dumb beats, lyrics skewering all that is hip, and plenty of a-go-go bells, the Soundsystem and its production alter ego, DFA, practically invented a new genre of smirking, so-dumb-it's-smart club music. But the band's sophomore full-length reveals a sadder and more serious side. There's still plenty of cooler-than-thou wit in tracks like "North American Scum" and "Watch the Tapes," but the silver creeps into LCD mastermind James Murphy's hair as he reflects on the death march of time -- every bit as inexorable as a four-on-the-floor disco beat. The relentless piano line that impels "All My Friends" through its exploration of regret and loneliness instantly connects the levity of Chicago house music with the gravity of Philip Glass. Even the fun funk workout of "Us v. Them" is anchored by a dark, Kraftwerkian groove and an even darker mood, articulated with lyrics of doom, hopelessness and resignation.