What to play for the first time on the new stereo is of course a decision that should not be made lightly. After all you can play the first song on a new stereo only once. Cause after that it would already be the second song.
I think I'd play a Mozart aria, turn the volume to maximum and see if I could shatter some windows.
From The Magic Flute, "The vengeance of Hell boils in my heart":
This is included on the Voyager Golden Record sent into space by NASA on the Voyager 1 & 2 spacecraft in case it should meet intelligent life.
(Don't try to sing this yourself it will rip your vocal cords appart)