Related Clues:
- Caruso and Domingo
- Paul McCartney plays them
- Group of like voices
- Some singers at the Met
- Notes we hear from singers in famous trio
- Lowest choir voices
- Wagner's Tristan and Parsifal, e.g
- Singers with a number of alternatives?
- Doo-wop group members
- Barbershop parts
- Caruso and Pavarotti
- Many stage Romeos
- Ones playing things low-key?
- They sing, or swim
- Singers producing notes for the audience