New REL R-528 Subwoofer break in period....

If there's one component that is less likely to be noticeably "break-in sensitive" it would be a sub. I have a REL and I think if it's working properly and set up right, Stringreen's comment is absolutely correct...any subtle changes in the amp response or speaker loosening up are likely to be minor at best as RELs can be seamless in how they integrate into a system.

I think there would be a break in of some sorts, at least the amp in the sub....thanks for the comments.

Indeed, but the nature of a good sub makes it less obvious.

I believe the sound of this REL has tightened up a lot.
There is no boom to it at all, just tight bass, slam and punch, it's very articulate too.
It seems to add MUCH to the rest of the sound, working with the rest of the music...I'm really taken back by it, and the musicality it has added to my system is huge. I'm thrilled!

The RELs can transform the sound of a system...it did with mine also as it just opens it all up amazingly.