Hi PC,
You'll be fine with the M80s in a room that size, because it's big enough to manoevre the M80s into an ideal location for a fine soundstage and smooth deep bass.
If your room were 8 x 10, say, or a den size, then I'd suggest a pair of bookshelf speakers--M3s or M22s--with a sub as an option, because it's much easier to ideally place a pair of compact speakers for a great soundstage in a small room than it is to locate a big pair of floorstanders with limited options in terms of movement.
Regards,
Alan
