My MB speakers took 79.45 years of 24/7 break in. I had to give them to Dr. Who to break in over several hundred years over several parallel universes. Oh, and I also had to add a bass trap 2 light-years wide at the back of the room....Then they started to open up a little. ;)
This is the most I have ever heard mentioned about break-in in a forum. The most I have ever heard about a speaker sounds terrible out of the box...I actually read in here that the speaker gets better and then gets WORSE and then gets better during the break-in period.....really?!?!?!?!? The impression I am left with is that there is just something amiss with these and it is far more likely that it takes a long time for your ear to adjust to, and appreciate, the type of sound these speakers make.
The boominess I keep hearing about is a *major* disappointment to me. YES, of course, you can rearrange/treat your house to help it, but the marketing touts non-boominess as a major plus for these speakers. It is true with 100% of speakers you can improve the bass with treatments and perfect placement.... It sounds like you are starting out with a boomy speaker to begin with and having to fix the boominess with heroic efforts that are not necessary with other speakers. With only small 4.5 in drivers - there should be 0 boom and the ported design of these speakers must have suffered to get the external design they wanted. People resorting to plugging the ports *seriously?*- something is wrong with the cabinet design.
