Maybe i should have been careful with my wording, the amp can be bias improperly and present ''excessive'' voltage at the output and be enough to burn the tweeter, can be clipping too early from being over driven in early stage/defective. Burning tweeter at this rate is not normal so i would check the wiring in the speaker/crossover to make sure everything is ok and if no joy get the amplifier bench check, hope this is better for explanation.