Broadway singers generally aren't very credible jazz-pop vocalists; Jack Donahue is an exception. This handsome University of Virginia alumnus and teacher, whose extensive theatrical credits include the Goodman's brilliant Floyd Collins and The Ballad of Little Jo at Steppenwolf, has a light, airy, plaintive tenor a la Gino Vannelli or Stevie Wonder. It's an expressive instrument that, guided by Donahue's sensitive interpretive skills, is well suited to elegant readings of tunes by the likes of Joni Mitchell, Leonard Cohen, Jimmy Webb, and Mary Chapin Carpenter as well as Floyd Collins composer Adam Guettel. His impressive debut CD, Lighthouse, includes Mitchell's "Little Green," Cohen's "Song of Bernadette," Burt Bacharach and Hal David's "Alfie," and a stylish, dreamy reading of the Nat "King" Cole classic "Nature Boy." For this engagement, he'll intersperse material from the CD with new pieces by vocalist Peter Eldridge, who'll join him for the late show next Saturday. Wednesday through Friday, May 22 through 24, 8 PM, Saturday, May 25, 8 and 10:30 PM, and Sunday, May 26, 7 PM, Davenport's Piano Bar & Cabaret, 1383 N. Milwaukee; 773-278-1830.