Just a thought, I believe if you have (2) 8-ohm speakers wired in parallel, that essentially creates 1 4-ohm speaker going into the amp. When you bridge an amp, it drops it's ohm load to half. So in theory, your amp will be producing a 2 ohm load, and if it is not 2-ohm load stable in bridged mode, clipping or cutting off(shutting down) can happen.