If it's happening with two different amps driving the same speakers then I think the speaker's load impedance is too low, likely due to incorrect wiring in the speakers, a shorted voice coil, etc. The low impedance draws too much current from the amp, triggering the amp's self protection feature to engage in order to protect the amps.
DATS tool from partsexpress easily measures the speaker's load impedance to make sure it's safe for amplifiers.