Not much of a believer in burn-in, but there was one time when my 5-6 month old Radius DDM was replaced with a new one (warranty claim). I knew it was new, because what I had was black, the one that came in was red (maybe stock issues after the tsunami disaster). The sound was different. Not bad, but sound placement was messy and the "smear" at the point where the bass/mids driver and HF driver overlaps was more apparent. Bass was a little slow too.

Let them run-in for a few days. Or maybe new cables can be the culprit.