May want to get someone to jump in here to verify, but if you paralleled each sub to each channel I think your giving the amp SAZ1500? a .25ohm load. Those amps I beleive have two channels but they are bridged inside. If that the case you need to try series each sub to each channel 2ohms each then internal bridge gives 1ohm. If it is running .25ohm I'm sure it is going to protect. Check the manual: http://www.sundownaudio.com/SAX-1200D,SAZ-1500D,2500D,3500D_manual_0512.pdf