No need to worry about ESD at equipment level. Only power surges and lightning strikes
I agee, that is my understanding also, that the cover would act as a faraday cage and current would take least path of resistance and go to ground. With digital devices and the ground plane of device also being attached to case I believe that is where the logic of 0V being suddently raised resulted in DAC going crazy and that is what actually caused the damage to my equipment as it went beyond full volume with something like white noise being output. So ancillary to ESD, but damage none the same. Happy with my solution, but I do concur that this is likely a solution for a non-existant problem for most. Did order two sets of spare ribbons as when this happened they were backordered two months. Fortunalely I had a one set spared. If I had to go two months without my two channel rig, I would be like Kurtz in Apocalypse Now "the horror... the horror".