There's really no need to be greatly concerned about maximum power ratings. The M80s are slightly above average in sensitivity and have no unusual power requirements. Either of those Marantz units can drive them to beyond safe(to your hearing)listening levels. However, Marantz appears to be a somewhat overpriced Denon, and unless there's a good reason to go with Marantz specifically, a similar Denon, such as the 3312(or the Onkyo 709)should be considered.

-----------------------------------

Enjoy the music, not the equipment.