Off topic: "Wagner's music is better than it sounds" was a line of the American humorist, Bill Nye. It is often attributed to Mark Twain, who liked and repeated it.
Singular nouns can be used DISTRIBUTIVELY with a plural verb as in , "A number of people are going to be late to my party" and plural nouns like opera and agenda can be used used COLLECTIVELY with a singular verb.
On topic. Try Gilbert and Sullivan's The Mikado. It's funny, has some beautiful music, and an entertaining plot. Opera combines music,drama and poetry, but for me the real lure is music. There is a stretch in Mozart's "The Marriage of Figaro" where I can't understand the words and I don't pay much attention to the plot, but song after song is of miraculous beauty.