TS, welcome. It depends how much "justice" you want. Your listening distance is a more important factor than room size. A room doesn't have to be "filled" with sound at the level that's sufficient where your ears are. An amplifier rating of 75 watts, such as the one in the E200, would handle a brief peak on the order of 102-103dB with M80s at a typical listening distance around 10 feet. This should be sufficient for most listeners who don't care to damage their hearing.
I'd suggest that you consider buying a unit with the very important feature of room correction processing. For very little more than the E200, if you want to go with Denon consider the 1613, which has Audyssey MultEQ. The 1613 factory refurb, which should be at least as reliable as a brand-new unit, is available from Accessories4less
for about $210.