Possible Clues:

• 'Otello' and 'Pagliacci'
• They may be light, using oxygen for a while
• "Carmen" and "Aida"
• "Grand" productions
• Performances at Paris's Palais Garnier
• Musical dramas are so fantastic when piano is included
• Schedule at the Met
• Composition of 'Der Ring des Nibelungen'
• "Fidelio" and "Otello"
• Dramatic musical productions