A male guitar player is vigorously singing a not to a song in a poorly lit room.
A man is singing indoors.
A male player is a man.  If the person is in a poorly lit room then the person is indoors.
A male is the same as a man and a room implies that he is indoors.
A male guitar player is vigorously singing a not to a song in a poorly lit room because he is singing indoors.