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Question: How big of a difference is there between the ANC7 and the ANC9 in sound quality? in noise cancellation?
Document: However, ATs have 3 different sound modes for different environments. You can clearly hear the difference between them when adjusting between the 3 modes.Quality:  Bose. I had a defective unit with my first ANC9. I heard a low level frequency motorboating sound in the right ear when I would tilt my head down. I sent them back and now have a error-free unit.
I've had these approx. two weeks now. They're good. I really like the sound, and the noise cancelling, but I have not had a chance to test them on a plane, or compare them with similar products. My biggest complaint is the noise leakage, mentioned by a previous reviewer. It's pretty bad. If you can put up with that, though, I recommend them. I also cannot tell a difference between the three noise canceling modes, but it's not a big deal to me.
I have a big head:  size 60, or around a 7 1/2 fitted baseball cap (for all you Americans), so whatever I say about fit is with regards to a big head.PRIORITIES:1. Comfort. No on-ears or IEMs.2 & 3. Noise-cancelling and sound quality (tie).4. Price.At first, sound quality was slightly more important to me than NC.
The sound quality compares favorably to my Grado SR-80's I use at home. The build quality is very good and the case is great, it does a good job protecting the headphones. Be aware the case is fairly big, larger than the ones for the Bose headphones they guy next to me used.Yes, they are fairly pricey, but if great sound quality and effective noise cancelling is important to you and you travel frequently, they are well worth it!
Sound quality is good: I don't have golden ears and haven't compared them with others but I am more than happy with the sound quality, the bass has surprised me at times. I should qualify that: the sound quality is good when noise cancellation is turned on. When NC is turned off the quality is relatively poor.
This has two effects, the advertised noise cancellation and the un-advertised one to improve the quality of the sound. I imagine this is common practice.As others have reported there is some hissing when the NC kicks in though I don't find it obtrusive and don't doubt that a plane's residual engine noise will swamp it.There is some leakage though not as bad as some have suggested, at least not at sensible levels.
Also, the noise cancellation is not as good as the Bose. When I switched the QC-2's on , the outside world vanished. With the AT's, it does along with a subtle hiss. This goes away the second audio plays, but in the &#34;silence&#34; it is not silent the way the Bose are. Overall, these are exactly what I wanted. better sound quality for music in a comfortable high end 'phone.
That's pretty much it.- Sound quality with NC off:  the sound is much worse. It's drastically different. Be prepared to create a different equilizer setting for "NC on" and "NC off". I've saved both equilizer settings in iTunes on my computer.- On my big head, the headband just manages to reach down low enough to get to my ears. If my head was "taller", they wouldn't fit.- Leaks sound.
While I'm far from an Audiophile, I have had different earphones and headphones the last couple of years. While I'm a big fan of Sennheiser, I have to say that after reading different reviews on the Sennheiser Noise Cancelling headphones, I decided to grab these. I was also in the market for the Bose 15, since everyone is raving about them, but the quality really threw me off (all plastic for $300 headphones, really?
Surprisingly, I found ANC9s were almost just as good as the Bose. The Sennheiser for some odd reason were terrible in noise cancellation.Comfort:  All were good in this category except the Sonys! Bose again took this category though they have a suction feeling on your ear. Your ear also tend to get very moist. Sennheiser took 2nd and the ANC9 followed with a close 3rd. The Sony are on-ear and for me, my ears were sore after 2 hours of listening.
Answer: I have both sets; used the ANC7 for about 4 years, now have been using ANC9 for about 1 year. The biggest difference in sound is that ANC9 have a much stronger bass. The noise cancellation is comparable, with ANC9 being marginally better.