It is **possible** that there is something else "spiking" in your system or power supply? Over the years I've twice had defective ampflification that toasted my drivers (usually at normal playback levels and once during power-up). A swap out of amplifiers remedied the situation. The funny thing was, these energy spikes were not even audible. I have a recording studio and over the years have also blown DOZENS of drivers in various speakers through over-driving or carelessness (easy to do at 2am after a 12-hour session), but I know which times it was beacuse the speakers were given more than they could handle and which it wasn't. Good luck.
Ray
Ray