BSO management also points to Lockhart's winning stage presence. While Levine, with his sore back, sits in a chair when conducting the BSO, the trim and stylish Lockhart moves fluidly, whether jumping into the air to punctuate the crashing climax of a rock song or swirling his arms gracefully to coax a lush movement out of the strings during a Samuel Barber piece.

Lockhart says he doesn't think much about his musical destiny or strategize about his career. The future is the next concert.

His path has never been predictable. Rather than serve as an assistant conductor in an orchestra after college, Lockhart spent his first five years teaching music at Carnegie Mellon University. He didn't get his first orchestra job until the Akron Symphony hired him as an assistant conductor in 1988. Two years later, the Cincinnati Symphony hired Lockhart for the same position. The BSO's librarian, a former Cincinnati staffer, recommended Lockhart to the Pops when John Williams — the film-score composer who replaced Fiedler — announced he would leave. On Feb. 7, 1995, Lockhart signed his contract.

The Pops job would be his biggest break. It would also become his greatest liability.

Life had changed. That, Lockhart realized quickly.

At one public appearance, too many people crammed into the room for autographs, knocking over his table. He became a target of gossip columnists, romantically linked to the head of a local neighborhood group, seen in a passionate embrace with another woman at Logan airport.

"The worst thing was, I was in California when I was spotted doing that," says Lockhart.

Only his marriage to Lin, in 1996, could put those rumors to rest. The moratorium ended with the separation last fall. The couple released a statement asking for privacy. Instead, Lockhart heard about how Lin had kicked him out for indiscretions. Oboist Blair Tindall, in her new book, "Mozart in the Jungle: Sex, Drugs, and Classical Music," wrote of a one-night stand she says she had with Lockhart while he was married.

"I can't have a cup of coffee with anybody without being told I'm sleeping with them," he says. "And it's absurd and hurtful and so profoundly stupid. There's an element of my life I've just lost."

He won't say much about the breakup with Lin, which is moving toward a divorce settlement. (She declined, through a BSO spokesman, to comment.) He says he asked for the separation, simply because they had grown apart. Lin remains with their son, Aaron, now almost 2, in the South End townhouse the family shared. While separated, Lockhart has been staying in a friend's vacant Beacon Hill apartment.