In the beginning, Los Lobos were praised for their purity—as Chicanos, Christians, and lovers of norteño. But it was after the compromises unfolded—beginning with the decision to play R&B and sing in English, and culminating with the bandmembers’ self-reinvention as far-out musical thinkers—that these guys got really interesting. Los Lobos’ last two recordings, Kiko and Colossal Head, and in particular the effort from the Latin Playboys side-project, are simply fascinating: slightly art-damaged Latino rock that generates a cacophony I’d guess comes naturally to artists defined less by a country than by a border. Warming up for A Tribe Called Quest last week, tonight’s openers Medeski, Martin, & Wood proved several things: that this jazz/funk trio has great taste in choosing who to support, that it regards grooves as untamable, almost spiritual things, and that for John Medeski organ playing is a full-body exercise. With Nil Lara at 8:30 p.m. at the 9:30 Club, 815 V St. NW. $20. (202) 393-0930. (Brett Anderson)