"Careful," Thymme Jones told me when I asked about his band's new album, What Sequel? (Pravda). "It's pop music." Indeed it is, though I'm not sure why that calls for caution--of all the strange things these supreme prog weirdos do, making the occasional pop album is among the least perverse. (The new one's their first in that vein since The Why Album back in 1994.) What Sequel? is a fairly joyful record, for all the dark, painterly imagery of its lyrics--it's full of improbable falsetto vocals and playful instrumental flourishes (brass, strings, flute, "fancy guitar") and from time to time deliberately parts the curtains of its cleverness to let its heart shine through. Cheer-Accident has stubbornly outlasted more than two decades of comings and goings on Chicago's music scene, and something about the intimacy of this record makes it sound like the music they might play when no one's around. Onstage, of course, there are usually plenty of folks around: the core lineup now includes guitarist Todd Rittman (U.S. Maple) and bassist Alex Perkolup (Bobby Conn, Lovely Little Girls), and the number of guests occasionally climbs into the double digits. Jones says the band will play for at least two hours at this CD-release party, and when I asked him what material to expect, he replied, "Everything. Just everything." The Lord of the Yum-Yum opens. a 10 PM, Empty Bottle, 1035 N. Western, 773-276-3600 or 866-468-3401, $10.