Headphone Reviews

Noise Canceling
Here again, Bose has made incremental improvements on their ability to isolate you from outside noise. I typically test noise canceling subjective ability by sitting in front of my computer speakers playing pink noise, brown noise, and a track of crowd noise in a bar both with and without music playing. While it did seem that the QC25 had slightly better noise canceling in the low frequencies, my overall impression was that the ability to reduce outside sound was nearly the same with both cans. Broad band attenuation measurements show the QC25 achieving about 2dB better isolation than the QC15.

In every other noise canceling test I've ever run, I found the QC15 to be clearly superior. My impression is that the QC15 was state-of-the-art in this regard, and is likely nearing the limits of what's possible with this technique. That Bose has only been able to achieve a modest improvement in this regard leads me to believe we're getting near the limits of what this technology can achieve in a consumer headset. (I wouldn't be surprised if aviation noise cancelers do a significantly better job, but they are aided by a large, somewhat uncomfortable design that would probably not sell well in the consumer market where comfort and styling is important.)

Sound Quality
Yup, you guessed it, the sound quality of the QC25 is a modest incremental improvement over the QC15. Both headphones deliver what I would characterize as a good, mid-fi response—overall balance and neutrality is good, but resolution lacks finesse. Comparing the QC15 and QC25 directly, I find the QC15 very slightly 'U' shaped with a slightly thick sounding bass to mid transition and slight emphasis in the mid- to upper-treble. The QC25 is very nicely neutral throughout, though possibly lacking very slightly in sub-bass response.

The most troublesome character of both headphones is a somewhat artificial sounding mid-treble response. In both cases, fast transients take on a slightly blurred character, 'S' can all to often sound a bit more 'TH' than called for. The biggest difference between the two is that the QC15 can sometimes take on a slightly exaggerated 'tingy' character in the mid-treble, where the QC25 is a little better behaved. Fortunately, neither headphone sounds harsh or strident to me in the least, and though the treble is a bit artificial, it's faults are also mostly benign.

Bass on both cans is good, but I felt the taught punchy bass of the QC25 was a good bit better. In fact, this may be the area of greatest sonic improvement over the QC15.

Lastly, unlike the QC15, when you run out of battery on the QC25 your tunes will continue to play. However, sound quality takes a serious hit, and the QC25 is a pretty murky mess when run in passive mode. Fortunately, both headphones run for 35 hours on a single AAA battery, which are easily found in the airport gift shop.

Summary
In my experience, Bose quite simply makes the best noise canceling headphones available today. While I've heard a few noise cancelers that sound a bit better, I've never heard one that isolated as well from outside noise...and that's the important bit for noise cancelers, isolation. If you're not in really loud environments, you're better off with a passive sealed headphone, but if you are in a very loud environment, what you need is great isolation first, and decent sound quality next. In that regard, Bose is simply the best, in my opinion.

The Bose Quiet Comfort 25 is an improvement in every possible way over its predecessor the Quiet Comfort 15..it's just that all the improvements are small. (When it's already very good it's hard to make it much better.) If you already have a QC15 I suggest that it's really not worth making the change, but... If you don't have the QC15 or QC20 and often find yourself in loud environments wanting to listen to some tunes in peace, the Quiet Comfort 25 is the way to go. A sanctuary of silence in which you and your music connect.

Bose has discontinues the Quiet Comfort 15 with the release of the QC 25, and as I hoped—and quite frankly expected—it easily jumps onto the "Wall of Fame" as an outstanding...nay, superior noise canceling headphone in most every regard. Nice work, Bose!

Video

Resources
Bose home page and Quiet Comfort 25 product page.
Head-Fi thread here.