What does Wagner’s Teutonic mythomania have to do with the French Baroque? Exactly nothing, yet there’s this: King Ludwig II of Bavaria, Wagner’s No. 1 patron, fancied himself a second Sun King. And so, the Royal Opera of Versailles has had the beguiling idea to present the “Ring” in concert over four seasons, piggybacking on the new production-in-progress at the Saarländisches Staatstheater, across the German border. Wherever he is, Ludwig must be purring with pleasure. —Matthew Gurewitsch