I have dozens of hours on mine by now. When I first listened, I thought they were a bit lacking in their lower range of 100-120hz or so. However, I discovered that the more I used them the better they seemed to become in this range. Also, through trying different listening levels I decided they are much better when pushed to at least a medium-high volume. They do sound full and rich being driven at around half the power (on average) of my M4.0T, and they do match up well with the Signature sub I'm using.
So, yes. I think there is a "loosening up" period as well.