"El Triste" performed by Ingihyunsang during Phantom Singer season one's special concert.
Members (from left to right in the video):
Paek Intae: Spinto tenor, classically trained. Leader of the group.
Yoo Seulgi: Dramatic tenor, classically trained.
Kwak Donghyun: Rock voice.
Park Sangdon: Baritone, classically trained.