Do you think driver “break in” is real?


Do you think “high end” drivers and crossovers typically need a “break in” period before they sound their best?  I ask because, I believe I’ve experienced this first hand in a very significant way. I replaced the tweeters (same exact brand and model as original) in my ACI Sapphire 25 year anniversary edition speakers and for the first week I thought I’d lost my all time favorite speakers. I was depressed!  So I just kept playing them…  finally after a couple weeks, I’m literally stunned and blown away at how incredible these speakers sound. Completely different than the first 30 or 40 hours after I put in the new Scan Speak tweeters. So I say break in period must be real - at least for some drivers. Has anyone else experienced this to a degree that is unmistakeable?  
Crossovers too?  I just rebuilt the crossovers for a pair of ACI Sapphire XL’s (using highest quality components- same values) and so far they sound mediocre. Hoping for the same result as my other Sapphires but after about 20 hours - no noticeable difference - and they do not even sound as good as prior to crossover rebuild. They sound flat, too bright with poor imaging - but for 10 to 15 years they were pretty great sounding speakers. Thoughts on crossover break in?? 
Thanks to anyone who responds!!  

sal1963

However, you can rev new speakers as much as you wish without damage. Just change the oil regularly.

"Once upon Your Dime...."

Does anyone other than me remember the suggested break-in time/mileage on cars and motorcycles?  The back-lot gray matter gurgles something about '500mi. or 30 days'....intelligent it was, for getting used to a new larger collection of bits 'o this 'n that with the potential of harm and/or demise of you at minimum?

Yup, thought so.
"Lets' do a fiery burn-out leaving the lot in the new 'Stang!"
"Doughnuts in that cul-de-sac?!  WTH Not....!"

Simple.

The warranty doesn't cover idiocy. 

Any spankin' new driver?  100hrs. at a 'civil' level; after that, it's your ears, spouse as exists, and your neighbors' tolerance level(s).

My DIYs' (not just a cabinet, remember?) get stuck on a streamcaster @ a low Muzak dB for 100hrs.; rising after that in 5~10 dB for a day or evening.

Those periods are inclusive of anything that I consider to be a suitable 'workout' for a 'newbie', all freq's all the time...

I won't try to break anything for a month.
Listening all the time, until the end.
Then I just enjoy. *S*

Imho...they're your speakers.  I don't have to pay for the shipping, making calls, emails..... 

For what it's worth, Andrew Jones was quoted as stating it's not a big deal.