When a powerful amplifier using +/- 50 volt rails (or higher) faults to a dead short to one of the power rails going out to the speaker then any D.C. coupled speaker in the cabinet is looking for damage. Usually the woofer only as the mids and highs are often capacitor coupled. The speaker often gets damaged as quickly as the fuse. Any fuse big enough or slow enough to not blow during sustained loud stage volume is usually too big to act quickly to protect the speaker. Speaker relays driven by 'D.C. offset' sensing helps BUT with power amps having rail voltages over +/- 50 run into another strange problem. The relay contacts go into continuous arc. The inductive kick back from the speaker starts the arc as the contacts open and the arc sustains because the contact gap isn't wide enough to clear a D.C. fault. To help relieve that problem often the power supplies are also commanded off in a soft reset mode. The drivers I have replaced most often (other than the total garbage like rockville, kracko, spark-o-matic, etc) were in the Bose 802's. Mainly the older ones, 8 x 1ohm speakers in series with a capacitor shunt that shorts out half of the drivers at high frequency leaving only a 4 ohm load and using the BOZO 'system controller' that adds 17dB of boost to the high frequency range. What a stupid idea!!