Hi Patchwork,
No, look closely at the impedance curve measured at the NRC facility and published at audiovideoreviews.com. Between about 150 Hz and 400 Hz, the M80's curve rides the 4-ohm line exactly, which is why it has a nominal 4-ohm impedance rating
Your question may be unanswerable unless you spoke to an engineer at Denon. If Denon has implemented a current-limiting circuit to prevent excess current flow at 4 ohms, the 1602 may power the M80s with no trouble but at greatly reduced power. On the other hand, the M80s are more sensitive and produce much louder sound than other Axioms with less power, so you may be okay. Perhaps other M80 owners will provide some feedback.
Regards,
