It's been my experience different brands break in at different rates - simply depending on the materials involved. Revel says no break in time required, Buchardt at least 100 hours.
My Thiels probably took 2-3 months to break in, and it was quite noticeable when they did. Bass isn't something you imagine. The midrange also lost some forwardness/harshness, and people who'd heard early then later concurred. However my Maggies sounded great from the start and changed very little other than a bit more slam. Think ribbons are good to go out of the box.
I'd imagine different drivers are going to go through changes at different rates, so yes I can believe it could sound worse for a bit until they all get in sync. What I plan to do when I get my next set is simply put on the Stereophile test CD, and run it 24/7, louder when I leave the house.
My Thiels probably took 2-3 months to break in, and it was quite noticeable when they did. Bass isn't something you imagine. The midrange also lost some forwardness/harshness, and people who'd heard early then later concurred. However my Maggies sounded great from the start and changed very little other than a bit more slam. Think ribbons are good to go out of the box.
I'd imagine different drivers are going to go through changes at different rates, so yes I can believe it could sound worse for a bit until they all get in sync. What I plan to do when I get my next set is simply put on the Stereophile test CD, and run it 24/7, louder when I leave the house.