truthfully i am not sure. the first time it happened i think it was just a bad driver from the outset as it happened about two months into listening. was using a reference Marantz amp at the time. second time was using the great PS Audio BHK amp so i know it was not the amp clipping or anything. granted i play it loud but no more so than when i had CS2's, 2.2's(blew a midrange once in18 years), and 2.4's (no problems). it seems to be the midrange driver and not the tweeter that goes. hard to figure but i am more judicious these days with volume. i measure it and rarely does it get about 85 db.