Could a cappella singing be the next big trend in musical entertainment? On the heels of NBC's "The Sing-Off," Alliance Theatre presents the musical AVENUE X, which pits the unaccompanied doo-wop and R&B singing styles of the early 1960s against each other. The band-free, eight-actor ensemble includes two local actor/singers, Rebecca Blouin and Neda Spears; J.D. Goldblatt of the Alliance's superb Jelly's Last Jam; and Nick Spangler, winner of the 13th season of "The Amazing Race." Director Susan V. Booth reunites with Jesus Christ Superstar GOSPEL singer J.D. Webster and music director Darryl Jovan Williams. Through Feb. 7. $25-$60. Tues.-Fri., 8 p.m.; Sat., 2:30 and 8 p.m.; Sun., 2:30 and 7:30 p.m. Alliance Theatre, Woodruff Arts Center, 1280 Peachtree St. 404-733-5000. www.alliancetheatre.org.