I will post the controversial answer- if you don’t like it when you first try it IN YOUR SYSTEM, no amount of break-in is going to change that. I’ve had many pieces of equipment, many that I wanted to like, but never one that transformed itself, over a period of time, into something manifestly different.
I see the the hours posted on forums about break-in times, and think to myself, there aren’t that many hours in a day to be doing that.
The second part of that joke is how many people, when selling equipment, usually say something along the lines of- low hours, hardly used, only in second system, etc., etc.
In my opinion, there are way too many variables to make a judgement about break-in affecting sound in a home environment.
I’m not a measurements guy; I believe that I might enjoy a piece of gear that measures poorly- but why would a manufacturer knowingly put out a product that takes 250-500 hours of break-in to sound good? This would mean that they tested various capacitors, power supplies, speaker drivers, wire, etc., etc., etc., ad infinitum. There are not enough hours in the day.