Custom indirect speaker protection circuit ?
Crowbar arrangement with thyristor that melts a fuse that is switched into the amp power cord, by vaporising the fuse the amp is off and no damage should occur. The detection of souch a failure can be done by placing a hall effect sensor on the input of the ribbons.
Just an idea...
Most of the time the energy stored in the capacitors of the amplifier is enough to destroy the panel. Quad ESL63 electrostatics had a crowbar arrangement with a thyristor that sometimes fused the output transistors of the offending amplifier ...