After reading about the H9 3rd Gen I also bought them to compare them to my trusted H9i's.
I am not an audiophile and I am exclusively listening to techno and old school house from my IPhone X via Spotify Premium or Soundcloud Go (high bit rate). So only AAC is relevant for me.
Compared them with ANC on, Spotify Premium, no burn in and both newest firmware.
- H9 have better bass, its stronger and tighter without any tonetouch settings. It also sounds more differentiated. At the same time its not rumbling or too heavy.
- H9 are less bright which actually makes for a more enjoyable listening experience and less listening fatigue than the H9i's (although with tonetouch, I never had listening fatigue even playing 10 hours or more very high energy techno sets)
- H9 just sound better and more complete in general on optimal settings than the H9i' s with different tonetouch adjustements
- H9 headband is slightly more comfortable than H9i's. Maybe this will be even more pronounced after a break in period.
- H9 ANC is definitely better. I played some plane cabin noise through my monitors at home and compared the H9 vs the H9i without any music on. I can turn up the volume of the cabin noises higher with the H9 compared to the H9i without hearing anything.*
- H9 turning ANC on affects sound quality less adversely than doing the same on the H9i's
- H9 noise floor with ANC on is lower
- H9 have voice assistant button (such an incredible feature /s)
So far everything sounds great, right?
Well, not really. B&O changed the interior diameter of the cushions and design of their lock mechanism, meaning you can NOT use the H7 or H9 first gen cushions on the H9 3rd Gen. However, you can use those for the H9i's.
Why is that important?
While the H9 3rd Gen cushions are less shallow than the H9i ever so slightly, they are still shallower than the H9 first gen/H7s by a few mm. The H9 3rd Gen are right in between the very shallow H9i and the least shallow H7/H9 first Gen.
Why is that a problem?
Due to the driver design of the H9i and H9 3rd Gen, the shallower design of their cushions makes extended wear (several hours) uncomfortable for me if not a very specific position. By using the H7/H9 first gen cushion I don't have that issue even after several hours.
Hence, while the H9 3rd Gen is definitely the superior headphone, I will be sending the H9 3rd gen back. After all, having amazing sound doesn't do anything for me if I cannot enjoy it due to comfort-issues. Also, the H9i's with tone touch adjustments are still amazing headphones, offer proximity sensor over the H9 (which for me works flawlessly) and have changeable batteries.
Nevertheless, I am annoyed that B&O changed the locking mechanism design. Seems like additional work and waste of resources to prevent customers from having the best possible experience by using better and more comfy cushions. I would be fine with B&O offering different cushion sets for the H9 3rd Gen, but they don't. The only reason I could think of is better seal and better ANC performance with the less shallow cushions.
I attached two pictures. One is showing the cushion shallowness comparison between H9i (left, most shallow), H9 3rd Gen (middle, slightly less shallow), and H9/H7 (right, least shallow). Second are my tonetouch settings for the H9i's which for me are the most enjoyable and closest to the H9 3rd Gens.
https://imgur.com/a/jyx92uW (For some reason I cannot embed the picture)
*P.S.: Interestingly my Airpods Pro's ANC (no music played) performed better than both the H9's 3rd Gen and H9i's against this sound