The M3 will be a very nice speaker. If I were you, I would seriously consider a small sub to complement such a small bookshelf. You don't need a huge beast, just something that will extend the bottom end down to between 30 and 40Hz.
I have listened to the M2's I use as a center and they sound great except the bottom end. This is in comparison to the M80 which has a wonderful bottom end. The M3 will have a little more apparent bass, but still...
Something like the EP125 would be perfect. If thats too big, maybe you can find a smaller sealed sub somewhere.
