The only problem is that the orchestra sounds the same while tuning as it does during the performance.
OK, I'm pulling your string. Though if I wanted to pick a 20th century opera ("Porgy and Bess" doesn't count, and "William Penn" is my favorite for personal reasons), it would be John Adams' Nixon in China, the minimalism in the music and a whole libretto of rhyming couplets without sounding like a libretto of rhyming couplets continues to fascinate me.
That work has a similar style of repetitive droning as Phillip Glass.
Not a fan