In an interview in January’s issue of the Wire, Matt Valentine posited a personal variation on Duke Ellington’s famous pronouncement that music is either good or bad: “It’s either sound with a fuckin’ message or it’s wimpy.” Valentine and his fellow singer, multi-instrumentalist, and messenger Erika Elder have amassed an impressive discography that includes stacks of CD-Rs on their private Child of Microtones imprint, deluxe-edition LPs on an assortment of tiny labels, and a new album called Green Blues on Ecstatic Peace that’s been sucked into Universal’s distribution pipeline. Taken a track at a time, their output is befuddling: I can’t find the common thread that might connect a gorgeously lyrical 12-string guitar fantasia, a wobbly Canned Heat-style boogie, a feedback excursion that could be the missing link between the final tracks of the Grateful Dead’s Live Dead and Sonic Youth’s Evol, and a take on Bo Diddley’s “Who Do You Love” that wanders so deep into canyons of echo it sounds like an outtake from Sun Ra’s Cosmic Tones for Mental Therapy. In concert these apparent contradictions often manifest themselves unpredictably. I’ve heard Valentine and Elder sound gentle or wild, openhearted or indifferent, simply marvelous or really bad–but never wimpy. Taken as a whole, their work seems to envision a synthesis of many strains of American outsider music–one that finds strength in diversity and solace in disorientation. Dirty American Organ, the duo of Scott Tuma and Matt De Gennaro, plays second, and Tirra Lirra opens. a 9:30 PM, Empty Bottle, 1035 N. Western, 773-276-3600 or 866-468-3401, $8.