So...ran into a new one for me.
Just finished an install, and something quite unusual popped up. But before I begin, I should preface this by saying the system is NOT ground-isolated (client couldn't afford it).
The (analog) install is clean as a whistle. No hum, no buzz, just beautiful, clean sound from stage to speaker. HOWEVER...
Static electricity is the death of it. It's a church, however the seating is on upholstered chairs. If someone sitting within a few rows of FOH shuffles around...SNAP! CRACKLE! POP! goes the PA. I kid you not. It's not exactly subtle, either.
None of the chairs are in contact with FOH. All chairs have rubber feet. In fact, the chairs within FOH, oddly enough, don't cause this problem (despite being the exact same type of chair). It occurs only with the chairs that rest on the carpeted floor (FOH is on a 1' wooden riser).
The board is an A&H ZED-428. With all of the inputs muted, and the master faders down, the system still pops. In every speaker. Main Left, Right, Centre, and Monitors. Even in the headphones. Disconnect the outputs from the console, and the popping stops. Connect an input directly into an output (thus bypassing the board), and it's clean.
I need to crack open the inputs into the console; they got tugged a little, and one of the grounds may have popped, and is now touching the shell. Even then...I hesitate to blame the popping on something like that.
The carpet comes into direct contact with conduit, though that occurs ~50' from FOH. And that particular conduit is electrical (though all the conduits in the building, including AVL, undoubtedly intersect).
Anyone ever had to ground a carpet before?