dino560b:
Just like a quality car, the drivers MA design are robust and intended to work for many years. In this case there are mechanical changes (to a degree) that take place during a running in period. And, some not so easily answered phenomenon. The net result is that MA speakers do take a lot longer to run in than some other brands. This is normally around 100hrs, but can vary on the type of program material and level played. Out of interest a lot of people leave them on whilst they are at work. Place the speaker face to face as close as you can get them but no touching. Wire one speaker our of phase as this provides a lot of acoustic cancellation and reduced the overall level considerably. MA even sell a burn in disc because then know this is a problem and always ensure speakers provided for review are run-in and carefully checked against the standard.
You will find that after a period of running in the speakers will sound smoother and more integrated. The music will appear to flow better and gel.
The new RX6 is a lot smoother and probably much better in the H.F than the RS series before if, but I assume you got an end of line deal, so great. Whatever you paid I think they are great speakers and very capable all rounders.
The RS6s are as good as it gets for floorstanders below the grand mark: They have a crisp top-end, informative and smooth midband and a fast, deep bass. Others on here regard the RS6s as Satan's armpits.... our gain.