If it is an early '90s Denon you can't assume the 55 watts can be reached before clipping occurs. To beat the gravetop of this old horse: My 105 rated AVR 3300 starts to clip at 84 watts. It is a 2001 model.
Just saying, if based on what John lays out you think you will often run over the mid-80s db then keep the effect of clipping in mind when you judge the sound of the M80s.