I got my Hadenys some days ago.
Fresh out of the box it sounded, well, strange. Muffled and bassy, and with an extreme volume mismatch between left and right channel, left was very much louder than right.
Focal recommends to burn in the headphone 24h at high volume. After doing this, the Hadenys sounds now more balanced, and after loading the eq setting from @Resolve the sound improves even more.
However, there is still a tiny channel mismatch, left is still a bit louder than right. So, I will return the Hadenys the next days.