The original members of X--Exene Cervenka, John Doe, Billy Zoom, and D.J. Bonebrake--reunited eight years ago, but they've toured so sporadically that any appearance is momentous. And why shouldn't it be? X was perhaps the finest band the California punk scene ever spit out, a live act so phenomenal they could actually get away with releasing multiple live albums. All you could ever want from sung romance is there in Exene and Doe's duet on "Johnny Hit and Run Pauline," his quivering, baritone croon bending and half-stepping with her feral yelping. Even the group's marginal mid-80s efforts, which could only pale in comparison to Los Angeles and Wild Gift, don't sound so marginal 20 years down the road. And if there are any naysayers still out there, last year's DVD release of The Unheard Music, the band's long-out-of-circulation 1986 documentary, should shut them up for good. The Rollins Band, together for the first time in nine years, plays second; the Riverboat Gamblers open. Sun 8/13, 6:30 PM, House of Blues, 329 N. Dearborn, 312-923-2000 or 312-559-1212, $35. All ages.