Mine is doing the same as well. I have tried replacing the HDMI, plugging it into a different port, testing the optical cord, resetting, and it is still crackling. I was going to ask for the subwoofer for Christmas and I don't think I will anymore because this speaker sounds awful.
My S/N is YL008K744049
SW VERSION 11.5.0 build 4235-95
Device ID 2A1178744049