Sweet Sorrow's voice

Actually I'm not their fan, but their voice is fantastic objectively. kk
Sweet sorrow is group name of singers. The group consist of four people. They sing a cappella and make harmony by their voice. It's really good to listen to. And their educational background is  also good! Korean say, they are 엄친아. (엄친아 means every mothers say son of mother's friend is always perfect person so Koreans who feel sympathy make the word 엄친아 and bename person who perfect in every field.)
This is their representative song that every Koreans known.

And they became famous by appearing in TV show 무한도전. They made a song with 정준하 in 무한도전, it, of course, was good to listen to! Their harmony is second to none in their harmony.