Running New York’s most high-profile concert hall is no picnic. So Robert Harth is an unlikely figure as Carnegie Hall’s latest top man: he is, by all accounts, soft-spoken and generous with his time, “the type New York power brokers eat for breakfast.” In fact, when the ill-fated merger of Carnegie Hall and the New York Philharmonic was announced this fall, many observers predicted that Harth would eventually be shunted aside by the Phil’s dynamic Zarin Mehta. Instead, Harth is now being celebrated for standing firm against the Phil’s desire to take over the primary programming responsibility for the hall, and for his commitment to broadening the scope of Carnegie Hall’s musical offerings.