The superb British soprano, as immaculately stylish as she was subtly expressive, has died at the age of seventy-nine. She was notable for her extraordinarily precise diction, which gave the musical line a tactile, etched-in-air quality. One of the finest nights of opera I’ve heard was Der Rosenkavalier at the San Francisco Opera in 1993, with Lott as the Marschallin, Frederica von Stade as Octavian, and Charles Mackerras conducting.