You sir are absolutely right, yes in fact I had full band set for the fronts, I forgot to mention it. And the peak LFE was the cause of the shutdown. Nice detective work there.

I can't recall if I tried with 8 ohms but I don't think I did.

It's interesting though that even the almost top of the line Denon which supposedly can drive 4 ohms in reality cannot.
For every expert, there is an equal and opposite expert.