For what it's worth... I have a Denon 4311CI which does have a 4 ohm option. Even so the amp shut down on big peaks driving the M80s.
Specifically, the new Tron movie. At the beginning where the guy finds his dad's basement setup and is transported to the underworld. There is a big thump sound and that triggered the protection circuit every time (the sound level was up obviously). No such issues with the ADA1000.
--For every expert, there is an equal and opposite expert.