@Klonatans Since I kinda derailed your question when I popped into this thread I'll try to add my two cents to your issue.
From my experience, the denon drivers benefit from burn in. My 9200's do sound different now than when they were brand new. Others have shared the same sentiment as well over in the 9200 thread. A quick search might yield something in this thread as well. What I noticed is more bass extension and the treble seemed to calm down a bit and it seemed less peaky but IDK entirely on that last point. Give your new pair some time and then do another comparison. It could also be the pads. Worn in pads tend to provide a better seal. Furthermore, worn in pads do alter the shape slightly and the driver could be closer to your head due to pad wear. Just all idle speculation into your issue.
It could also be a QC thing. Check out this video from Denon Japan for the
construction of the D9200. At around 1:11 they show the headphone going through a QC check for audio and it shows acceptable FR ranges and the FR of both L and R on that headphone and the left channel only matches 63% to their reference response (or 63% to something. Maybe the other driver. It does not tell us exactly what). I don't know what the QC process is like for the 7200 considering a different factory but it is safe to assume that it is equal to or less than the QC of their flagship made in their Japan facility. It could just be that your headphone does sound sonically different to your old pair but still passed QC.