I have an SWR WM 4x10T powered by a WM 4004 head. On a couple of occasions, I've gotten a nasty crackling noise while playing from the LeSon piezo tweeter. Both times I stopped playing, checked gains, the tweeter switch on the back of the cab, volume levels, etc., and then it was fine. I'm pretty certain that in both cases, my clipping LED did not light. I only had the master to 3 and the gain about halfway. If I crank it, I can make the clipping LED light, so I'm sure I don't have a dead indicator. One of these times was with a friends Rickenbacker. The other was with my Fender Jazz Deluxe V. It isn't the bass. My current thinking is that it might be the bass cable (which I've had for about a year and a half now.) The cab was new when I bought it, so if there is any damage, it had to be in the showroom. Any ideas?