Does it happen with all input sources? I ask this because last night I heard some crackling in on of my rear surrounds while watching a movie on TV and like you I was immediately concerned. After testing other channels, a CD, A DVD and the radio, and unable to replicate the "crackling" I was able to determine that it must have been in the movie track itself and this was reinforced when the movie was over the "crackling" went away on that particular channel. Good luck and I hope it is something easy