Eleventh Dream Day are the best rock band to come from Chicago since Bo Diddley helped invent the genre here, but bad luck and bad timing may have consigned the group to obscurity. When they started in 1983 Chicago was a rock 'n' roll backwater; their incendiary live shows and splendid first album, Prairie School Freakout, helped return the city to the rock map. But pioneers rarely reap the rewards of their efforts, and an inept record company kept Eleventh Dream Day sidelined while their contemporaries became stars. In the past couple years they've been reduced to a side project of their offshoot bands Freakwater and Tortoise. But that hasn't affected their volatile blend of terse, indelible songs and highly flammable guitar duels. For this performance, the band's first in more than a year, guitarist Rick Rizzo and drummer Janet Beveridge Bean (both also sing) will be joined by Yo La Tengo's bassist James McNew and guitarist Ira Kaplan (regular bassist Doug McCombs is in Denmark with Tortoise, but he'll rejoin Eleventh Dream Day to record their new album next month). Kaplan's appearance with Eleventh Dream Day here in 1994 was one of the band's best ever--this one should not be missed. Also appearing on this last night of the Save Lounge Ax benefit are Yo La Tengo, Seam, and Red Red Meat. Sunday, 7 PM, Congress Theater, 2135 N. Milwaukee; 252-4000.