SECOND BEST CONCERT OF THE PAST TWELVE MONTHS Wilco at the Pompano Beach Amphitheater It was difficult to tell who was more perplexed by the size and passion of Wilco's crowd: the band's singer Jeff Tweedy or the Pompano Beach Amphitheater's security guards, who spent the early part of the evening shooing audience members away from the stage and back to their seats. Finally, with obvious bemusement, Tweedy urged his screaming fans to "come on down," Let's Make a Deal-style, and the 2500-strong crowd did just that, surging up out of their chairs and past the now-helpless half-dozen guards, creating an instant general-admission concert. Wilco has had that kind of effect on listeners these days, and based on that night's performance, it's not hard to see why the band has moved far beyond its cult following. What was once a solid alt-country outfit has grown into a purveyor of sublime pop, albeit one whose sing-along choruses are filled with paeans to clueless theologians, collapsing buildings, and guilt-laden drug deals. As for those Beatles-esque melodies, they're similarly filled with a cockeyed spirit, one apt to erupt into a speaker-shredding guitar solo that threatens to derail the entire song. Likewise, while Tweedy himself never shies from reaching for that perfect note, his voice is prone to cracking along the way, aching satisfyingly. The Wilco guys certainly remain dark-horse candidates for rock and roll stardom, but it's that very off-kilter sensibility that makes their music so memorable.