Stephin Merritt has come out of the closet: Of course! You’re a theatrical composer! It must have been so hard passing as a pop singer all those years. The leader of the Magnetic Fields and sundry other indie broods slides into musical theater so easily, one has to wonder how he was ever mistaken for a Brill Building or new-wave revivalist. At their most theatrical, these 26 ensemble recordings (from three productions with director Chen Shi-Zheng) set scenes with charming detail: We find it necessary to take a spot of sherry, and so we find a very secluded sanctuary, sings a character on “At Madam Plum’s.” And the characterizations are even more fun, especially the gleeful maniac in “What a Fucking Lovely Day.” The palette, mixing Chinese instruments with echoes of American folk and Tin Pan Alley, bears none of the bombast that makes Broadway so alienating to pop fans, and Merritt’s preciousness seems unlikely to irk fans of musicals. So glad to finally meet you.