OK, heres some examples using the M80.
To listen at 90 DB with 15db of head room for peaks:
8' listening distance = 50w
12' listening distance = 103w
15' listening distance = 175w Look ma, I need external amps!
18' listening distance = 275w mine's bigger than yours is
To listen at 95db w 15db headroom
8' = 157W WHAT?? YOU LIKE MY EXTERNAL AMPS?
12' = 344w
15' = 509w
18' = 760w
In my apartment I can listen at reference from my kitchen. In some of the rooms you guys have, my receiver would barely keep up in the main room.