It's typical to pick up 1-2dB of bass during burn-in and to have the highs smooth out.
There are multiple ways to listen to and perceive bass on headphones, the original AEON Closed was tuned to a pretty linear response on a fixture. Now if you listen to certain music like classical that linearity shows up very well with the midrange, however, due to the way we perceive bass, which includes physical bone-conduction from speakers/live sources, many people need a boost in the bass to perceive headphone bass as flat, and this is particularly true when the headphone has very low THD, as ours do, because it's easier to hear the bass harmonics than the fundamental, especially at lower volumes. A lot of where a person falls on the perception of bass output I think depends a lot on whether the person LISTENS to the bass level of FEELS the bass level, or a blend of both.
For this reason we've switched some models to have boosted bass so the perceived bass feels closer to live or speaker-based music. That said, there are many other factors and some headphones like VOCE sound like the bass is boosted when it's ruler flat.
Of course Dakoni now makes a pad that is designed to make the AEON 2 bass linear like the original AEON Closed so you have paths to get the sound you want through our pads, or Dakoni.