You are probably exceeding the rating for the speakers. This amp can deliver 2000 watts to a 2 ohm load. You would need MASSIVE speakers to take this much power. The best of speakers can probably take an HONEST 400 watts... although most LIE big time about their capability. ALSO the spaekers have to have an ENGINEERED enclosure when run at high power. It is unlikely you cna drive 3 speakers evenly so they share the power... one is gonna get fried first...
then the remaining ones will fry...

ALSO make sure you don't send music pitches higher than what the speakers are designed to take. Make sure your crossover prevents highs from getting to subs.