When a recording of Bruce Springsteen’s “Born In the U.S.A.” blared through the speakers at Invesco Field at Mile High after Sen. Barack Obama’s acceptance speech Thursday night, it was official. Springsteen, rumored all week to close the final night, would not show. Thus did ex- Doobie Brother Michael McDonald have the last musical word a few hours earlier. Actually, the pre-Obama music was kind of a letdown: John Legend and Will.i.am brought YouTube to life with “Yes We Can,” complete with a huge live choir and Obama speaking on a video screen overhead. But all that activity on stage as delegates and spectators were filing in was confusing and the performance fell flat. Sheryl Crow did three songs with her band, opening with (altered for the occasion) “A Change Will Do Us Good.” Stevie Wonder did two, beginning with an unreleased obscurity, the hymnlike “Fear Can’t Put Dreams to Sleep,” then emphasizing “good-BYE” in his Motown chestnut “Signed, Sealed, and Delivered,” which might have been dedicated to John McCain and the Republicans. On the floor, near CNN’s podium, the Rev. Al Sharpton told Rolling Stone he first met Wonder at a concert by his friend, James Brown, in the early ’80s. Then he lamented the lack of cutting-edge hip-hop surrounding this Democratic campaign. “I know there was a lot more hip-hop presence in ’04,” he said. The rev, by the way, has gospel, JB, Jay-Z and Mary J. Blige on his iPod.