I got my H9s yesterday and was able to do some testing with them last night. Herewith a quick summary of my conclusions.
ANC - Using my recording of the engine noise from a 737 flight I was on, played back through my hifi system, I tried out the noise isolation on the H9s in comparison to my H7's (which I know don't have ANC, but are the headphones that I was planning on replacing with the H9's), my wife's old Bose QC 15s, and my current in-flight choice, my Shure SE846 IEMs with Comply Isolation Foam Tips. The H9s placed firmly in the middle of the group. They were very slightly better at isolating the engine noise than the SE846s, but slightly less effective than the Bose QCs. When you consider that those Bose headphones are now pretty old, and certainly don't do as good a job as the newer versions, this shows that the H9s are considerably less effective than a new Bose set would be. Of course this isn't a revelation to anyone. What I think is interesting is that the H9s are only very slightly better than simple passive isolation, and I do mean slightly. For me the quality of the sound is more important than some background noise in the very quiet passages, which is why I love the SE846s and based on my testing would not change them for the H9s for flying. I discovered one factor that might influence some buyers, the ease of switching off the ANC on the H9s with a simple vertical swipe on the right earpiece. Without the ANC on the H9s, like my H7s, do very little isolating, so on a flight it would be very easy to kill the ANC so as to be able to hear an announcement or the flight attendant, something that is not easy with my IEMs!
Sound Quality - I have a pair of H6s which I really like (they are the original version. I tried the 2nd version but much preferred the sound of the originals), a pair of H7s, a pair of H5s and a pair of Sennheiser HD 800S headphones, as well as the SE846s. I have had a set of H8's but didn't like the sound quality. For the H9s, my comparison was with the H7s not the Sennheiser or Shure. Clearly I am a fan of B&O, however, like other posters to this thread, I was not happy with the sound of the H9s. I found the low end to be confused in comparison to the H7s and the real killer was testing some tracks with a strong bass beat to them. The H9s rendered the sound as an unpleasant thump, rather than a note. The same tracks on the H7s managed to maintain some musicality to the sound. I used the Beoplay app to try to overcome the issue on the H9s, but doing so compromised the sound too much to be acceptable.
Bluetooth - Pairing seemed to be slightly more difficult for the H9s than for my H7s, but on the plus side, the H9s showed no sign of the slight background hiss that sometimes was just audible when a track was starting up on the H7s bluetooth connection.
Comfort - Whether it was just that my H7s have been used for a while I don't know, but the H9s were not as comfortable. The clamping force was a little higher, the pads were a little stiffer and the shape of the pads was more straight sided. I do have the grey version of the H7s whose tan leather is beautifully soft and was comparing to the black in the H9s.
Conclusion - I could not live with the bass sound on the H9s and have returned them. Maybe it would have got better if I had burned them in for a hundred hours, but even then, there wasn't sufficient advantage to them to justify the expense of replacing the H7s. If you are looking for a pair of ANC bluetooth headphones for flying where you are prepared to sacrifice some ANC performance for sound quality, I think that these fall just short of meeting that requirement in both directions, not enough ANC, and too little sound quality. Of course, all of this is subjective and you may well find them ideal. Without doubt they are beautifully made and a joy to own and handle.
WHY! boo hoo
