Vike, welcome. As Rick and others commented, the M80s might not be your best choice in that room. With reasonable speaker and listener positioning it appears that you wouldn't be more than about 6' away. The drivers should have enough distance to "blend", and with the size of the M80s you probably wouldn't really have enough room, so that in my view is the problem, rather than any sort of "overpowering", because the volume can be adjusted to suit the room.
I tried my M22s in various sized rooms, including one just slightly larger than yours, and believe that they would be a fine choice for you when coupled a good sub.
