Wagner’s “Die Walküre” is set to appear on Great Performances at the Met on August 12 at 12 p.m. The opera will feature Robert LePage’s famed production with Christine Goerke, Greer Grimsley, Stuart Skelton, Jamie Barton, Eva-Maria Wesbroek, and Günther Groissböck among the cast members. Philippe Jordan conducts the second installment in Wagner’s famed tetralogy. Of the opera’s opening performance, {…}