I know what you are saying about checking and rechecking the wiring but it isn’t that type of crackling sound. It’s not a short, soldering joint, or other type of electrical crackling and it only happens with the 8 inch rather than the 10 and only happens when a guitar is being played through it.
I usually play right at the point of clean/overdrive. I think some people might describe the crackling as just a jump to higher gain or from overdrive to distortion. It just seems very abrupt and I’d like to figure out a way to smooth out the abruptness of it.