The "one particular song" part makes me wonder if it might be in the source material. Is there somewhere to find a recording that's just a frequency sweep, and use that to see if the speaker cabinet has a rattle at a specific pitch?Question here for owners. Last night as I was listening to some music, pretty loudly I might add, I noticed that one of the speakers sounded a bit distorted, but more like something was rattling on the inside when certain very specific low frequencies were being played in this one particular song I was listening to.