I received my M4's last Wednesday and have been breaking them in over the past week. So far have about 50 hours on them and thought I would share some of my thoughts. When I first set them up, I positioned them in the exact same location as my previous speakers (Dynaudio Special 40's). I am using my formal living room in an early 90's style house and the room is not symmetrical. For looks I had positioned the speakers and rack to be centered around the window but that puts the right speaker about 10 inches from the wall. The left speaker probably has 15 feet to the right wall as that area is open and flows into our entry way. Even with this setup the M4's with about 1 hour of break in sounded better than my Special 40's!

I had a bit of time over the weekend and built some acoustic panels for the room so I decided to move the M4's over a bit to where they will ultimately be, this throws off the room a bit due to the placement of the window, but hey, this is a listening room, right

. I plan on adding one or two more panels to my left wall, am working on those right now. The right M4 is now about 2 feet away from the right wall, they are about 4 feet away from the front wall.
Here is a pic of the current setup, please excuse the mess as I was hanging panels and haven't moved the coffee table into the proper place. Will also bet getting some shorter speaker wires. Plan is to get a longer curtain rod and more curtains to extend out to the left, and with them closed it will appear that things are centered. The bookcase will also be coming out of the room.

Left side

Right Side

Now having about 50 hours on them, having them better positioned in the room and with the room treatments up all I can say is they sound incredible! Everything is amazingly clear, the sound stage is very large, instrument separation is crazy good. The bass is fast, clean and tight. I could get my old system to make more bass as I had 2 sub woofers hooked up, but the bass from the M4's is just better, not stronger, just right on all the songs. I noticed that all of the music now sounds lifelike and natural, even my wife noticed how much better my system sounds.
I keep hearing about how these really open up after several hundred hours of breaking and I can't wait. If they don't get any better than they are now I will still be thrilled!