It depends on the situation. When somebody gives you an opinion and you say "sounds good", then you just say. 좋아 / 좋아요 - good 그래 좋아/ 네 좋습니다 - Ok, good. When somebody introduce you a good music or sth and you say "sounds good" then it is like 이 노래 좋네 / 이 노래 좋네요 - this song is good. 듣기 좋다 / 듣기 좋습니다 - it is good listen to. hope it helps