I realize this thread is older, but, I came across it searching for "Magico A3 break-in" on the web. I purchased a pair of A3's a couple weeks ago and initially wanted to put a gun to my head. What did I do? They sound awful.
I've owned numerous speakers over my 30+ years as an audiophile so I'm no stranger to speaker break-in. Generally, out of the box, and especially at 50 hours or so, most are listenable. The A3's don't follow that scenario, in fact, they may be the worst sounding "out of the box" I've ever owned. I quickly went searching for owners who could qualify my observations, but a couple times here I read "they are good out of the box". For me, nothing could be further from the truth. Prior to 60 hours there was no sparkle on the top... no cymbal trails, etc.. Mid-range was compressed and uninspired. Bass - boomy, overbearing. Mid-bass - running up into the mids and obnoxious. I've now surpassed 125 hours and the mids and top end are starting to open up. There was a bass drop at about 75 hours and the bass has come back tighter and more defined. I sit here listening and realize there is a ways to go, but things are dramatically better.
Now, these are incredible speakers as evidenced by all of the reviews and my own listening session in the showroom. I'm just starting to hear what I had hoped for when purchasing.
I wish I would have read some of the same observations before freaking out and thinking I just blew $12k. I was not for-warned about this upon purchase and I can't imagine others not having these experiences. Just wanted to share in case someone else is in the same boat