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.
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.