I hope break in is true

You haven't said much about who or what you purchased, but the answer is generally Yes! It will definitely improve! It will take about 100 hours to start sounding fair to good. After the first 100 hours the machine will settle in. Congratulations and good luck.

Break in is a real issue, althought I don't know if it will result in the improvement you are after. I'm breaking in a new CDP, for the first 50 hours it was brittle and dry sounding - all of the notes sweemed to have their endings chopped off. It is slowly coming to gether now after 100+ hours.

I just recapped some amps. 1st 24 hours rolled off highs, and ill defined bass. I'm now about 40 hours into break in - my bass is filling out and becoming tight - the highs are reappearing. FWIW I have other quipement connected to quickly verify the breakin process.

It's real..............

after 10 years in audiophile, the answer is NO.

Personally, in my experience, I believe the break-in myth is highly overrated. Maybe folks just get used to the sound of new pieces after a hundred hours or so, but my general experience has been that if it sounds poor out of the box it may not change all that much with time. These comments apply mainly to solid-state electronics and assume your allowing for proper warm-up time (at least a half hour to an hour).

The exceptions to this would be tube gear (which definitely changes as tubes burn in) and speakers, which have mechanical suspensions that need to loosen up a bit.

If you bought a solid-state preamp, it may smooth out a little with time, but I doubt that its general character and dimensionality will change significantly. Leaving it on for a few days and letting it stabilize should help smooth it out and perhaps let it bloom to some extent.

My advice is to pay attention to detail and try different power cords, interconnects, and footers if you have those items to change out and experiment with. Cables that worked well with your old preamp may not synergize as well with the new piece. You should know in a week or so if it's going to work out for you.

I am reluctant to give info about the pre I am talking about. I would not want to disrespect the dealer. He was wonderfull about the whole purchase. He has nothing to do with the unit I purchased.
My thought is "it is what it is"
Might even be the amp. I will do some work with it this weekend. It's a Audible Illusions S120 that I just picked up on ebay.