That Jim O’Rourke’s two concerts this week–which he says will be his last in Chicago this year–are going to be completely different from one another won’t surprise his fans: O’Rourke’s resistance to doing the same thing twice has become somewhat of a calling card. On Friday, opening for tropicalia pioneer Tom Ze (see separate Critic’s Choice), he’ll perform songs from his most recent album, Eureka (Drag City), as well as a few from his previous one, Bad Timing. While O’Rourke broke his own rule by performing Eureka’s opening cut, his version of Ivor Cutler’s “Women of the World,” at quite a few shows last year, this will be the first proper live treatment of these songs–and, in typical O’Rourkian fashion, the last. Eureka is O’Rourke’s sometimes humorous, sometimes caustic response to the breakup of Gastr del Sol, the consistently experimental but occasionally precious outfit he fronted with David Grubbs for five years. The lyrics are barbed, but the message is in the music as well: Camoufleur, Gastr’s last recording, flirted with pop, but Eureka wallows in it, from the woozy cover of Burt Bacharach’s “Something Big” to the schmaltzy hot-tub theme “Through the Night Softly” (featuring Ken Vandermark’s hilarious impersonation of 70s-era David Sanborn) right down to the obscenely pink album cover. Even at his most excessive, though, O’Rourke laces the cotton candy with evocative textures, and his arrangements are consistently and genuinely gorgeous. The ten-piece band he’s toting includes violinist Julie Pomerleau, Bobby Conn, Frank and John Navin of the Aluminum Group, and Darin Gray on bass. Monday’s lineup will be much slimmer: O’Rourke and Swiss percussionist Gunter Muller, with whom he’s made three recordings for Muller’s For 4 Ears label. On Slow Motion, the first, he sent waves and splashes of noisy guitar and electronics over Muller’s wonderfully disjointed drumming; the most recent, Weighting, is dominated by organ drones, pointillistic piano splatter, skittering electronics, and somnambulant percussion. (Certain bits actually recall Gastr’s Upgrade & Afterlife, to which Muller contributed.) This gig, which is supposed to feature solo sets from both musicians as well as a duo performance, is Muller’s local debut. Friday, 8:30 PM, Park West, 322 W. Armitage; 773-929-5959 or 312-559-1212. Monday, 10 PM, Empty Bottle, 1035 N. Western; 773-276-3600. PETER MARGASAK