Filling in on the podium for the first two performances of the run, on March 30 and April 5, will be Fabio Luisi, who is already in New York to lead the Met's current production of Strauss's Die ‹gyptische Helena. Replacing Armstrong Apr. 9-16 and Apr. 28-May 8 will be Marco Armiliato, now conducting the Met revivals of Andrea Ch_nier and La traviata. The conductor of the performances on Apr. 19, 21 and 25 will be announced at a later date.