Following up with this previous comment:
After having my Pro 82 for over three months now, I still agree to myself to most of what I wrote in there some months ago. Except perhaps for my impressions on their soundstage, which may need some slight amendment (for the good). This change of mind came after buying the Fidelio X2, which are supposed to deliver a huge soundstage, and comparing them directly, side by side, to the Pro 82. Since the X2 are a quite popular headphone, I will probably post something more elaborated on this comparison later on, in case it's helpful for others.
I thought it would be good to elaborate a bit more on it, since although it may be seen as an unfair closed- vs. open-back headphone comparison, those Philips might be a good reference point to some people.
So at first, right after my X2 arrived and I put them on to try, I was quite surprised by how the Pro 82 seemed to be much more detailed and resolving! Especially in the highs and lows (their bass response is quite unbeatable for any open hp, I believe). X2 seemed to be superior in the vocals (both in tonality and presence); they are probably not the best Hi-Fi experience out there, but they do deliver a very pleasant overall sound.
I was told that the X2's characteristics were mids-forward with a grainy treble. I think the X2 are not so much mid-forward, I would say that they are more balanced with vocals than the Pro 82, which is clearly a bit recessed. To me, the X2 are clearly worse in the low frequencies, and not in quantity but in quality. They do have enough amount of bass, not overly bassy, but perhaps lying in between the Pro 82 with the bass port closed and opened by one notch. They are softer in the highs, not muddy at all but with a lower impact than the Pro 82, which can be good or not depending on your preference (of course). I think this feature makes the X2 quite tolerating to bad audio sources, while the Pro 82 will very likely more easily pinpoint aspects of a bad recording.
After some burn-in period and a more detailed one-to-one comparison, the X2 were finally put for sale... And it was after this experience that I thought I would need to reevaluate some points of my previous review on the Pro 82.
The main point is about soundstage. The Fidelio X2 are considered to have a wide, if not huge, soundstage, which honestly I couldn't really feel that much in my tests. Obviously, being an open headphone adds a lot to the feeling that you are in a more open space, but to me never to the great extend of feeling like in a full room. I'm quite new to Hi-Fi and perhaps didn't understand what people refer to good soundstage: I thought it was about resembling the experience of listening to speakers, which TBH I never felt with any headphones yet. Taking the X2 as this good reference for soundstage and having said that the Pro 82 have a compressed spatial representation of sound (left-right game), I now believe that maybe I should rephrase it to a “good soundstage”. It is the clearness of the Pro 82 and the always-present highs what makes them feel that way, I believe.
On the other hand, the X2 made me realize more about some of the Pro 82's flaws. Specifically the vocals. Swapping headphones in a sort of a quick-and-dirty A/B test, made me hear the voices in the Pro 82 sounding a bit phony and clearly shifted to the highs, every single time, besides them being recessed (as commented in the past). After a little while, my brain somehow gets used to it, but at first it is always appreciated as not that natural. Doing the opposite test, from Pro 82 to X2, I could always hear a big improvement in vocals.
Highs in the X2 are much milder, I'm not sure if the correct term would be rolled-off, because I could hear all frequencies were present, but in a very gentle way. Which in comparison makes the Pro 82 to me much more revealing and enjoyable. I've noticed, again, perhaps they are a bit accentuated (on purpose) over what should be a more natural sounding.
It is the bass and the highs the main reason why I'm not keeping the X2. The bass is quite good though, but I prefer the slightly over-present highs in the Pro 82 than the softer ones in the X2. The X2 would not be used that much since the Pro 82 are much more revealing and fun, while giving a more coherent/complete experience of music and vocals.