There don't seem to be exposed connections from the back, so there aren't any obvious shorting concerns.

Due to the open design, you can see right into the headphone itself, leaving a barely-covered driver. This makes sense, and is something that's present on a lot of high-end headphones: No sealed chamber means less pressure resisting the moving speaker element, allowing the headphones to more closely approach optimum performance. Sometimes manufacturers decide to add in foam or another porous material to protect the back of the speaker from foreign-object damage, but these don't seem to have that. Don't fret, though, as there don't seem to be exposed connections from the back, so there aren't any obvious shorting concerns.

If you're looking for a comfortable set of headphones, it's really hard to beat the type of band that Audio-Technica fits their high-end headphones with: The springloaded paddle system automatically adjusts itself to your head, and the huge ear cups spread the light load over a large surface area. If you have an exceptionally large head you may run into issues, but this design is geared towards hassle-free comfort—and it shows.
For those not used to the rather odd-looking ATH-AD900x, using these cans might be a bit of an adventure. However, all you need to do is just put them on—no adjustments, no futzing around with the band—nothing. Because these cans don't need much juice to run properly, you can also plug them into just about any source and get near-ideal performance—you don't need an amplifier or any special equipment for these.

As long as you're listening at a comfortable volume you can go for hours and hours in one sitting.

Even though some over-ear headphones can trap in heat and make you uncomfortable, these do not—as long as you're listening at a comfortable volume you can go for hours and hours in one sitting. Unfortunately, because the cable is very long and unwieldy, these stay by the computer. That's really okay, as using these outside or around others would be a bad idea: Not only do they let in just about every sound around you, but open-backed cans typically leak a lot more sound than their closed-back brethren.

If you're worried about things getting inside these headphones, I would recommend finding a way to hang them or keep them off of the desk somehow—while dust can easily be blown out of the backs, accidentally spilling coffee on your desk could spell disaster if it reaches your headphones. That's not an inexpensive replacement, either. It's up to you, but its saved me on occasion with my own headphones at home.
Considering how well their predecessors scored in our tests, we had very high expectations for the ATH-AD900x, but they're a bit different than the ATH-AD900. While it's not uncommon for manufacturers to channel the image of their older headphones for newer models and change the performance somewhat (e.g. AKG's Q701s vs. the older K701s), the ATH-AD900x has a few more places where Audio-Technica took some liberties, but that's really fine, it's just notable that they sound a bit different than the older ATH-AD900.

Some of the more sibilant sounds like cymbals and fricatives will be reduced in perceived loudness by over half.

For starters, where the ATH-AD900 reproduced most sounds at the same volume more or less, the ATH-AD900x does not—some of the more sibilant sounds like cymbals and the highest octave of a piano will be reduced in perceived loudness by about half. Some people enjoy that, especially when bass sounds are quieter too—it's not uncommon to see these frequencies reduced in volume. However, this does mean that the ATH-AD900x is not the best choice when mixing songs or other audio files because what you hear through the headphones will be noticeably different from what you'll end up with.

The rest of the performance points are notable in that there isn't much to talk about: It's a good thing when I'm not harping on problems like high distortion or tracking issues. If you own ATH-AD900x headphones, you know that you can listen loudly if you so choose without worrying about audible distortion, and there are no added echoes or buzzing. They may or may not have the frequency response you enjoy, but that's the limit of their possible mismatches with what you'd want in terms of audio performance.
If you're looking for an open-backed set of cans to adorn your skull at home, the ATH-AD900x will do so in style, clad in backs that are reminiscent of black metal fishnets. Just keep in mind that these headphones mark a slight departure from the previous iteration, as they do not have a completely even frequency response—they underemphasize some of the higher sounds, and that may or may not fit with what you're looking for.

With the change in performance, Audio-Technica appears to be moving to appeal to consumers with a different sound. However, this may not be a welcome change to some select demographics—if you're looking for a completely flat response so you can easily equalize your music, these are not the cans for you.

All that said, the ATH-AD900x is yet another fielding from Audio-Technica that is interesting in its own right, and definitely worth a look if you need a set of cans that are super-comfortable, attractive, and relatively affordable as an entry into the world of higher-end audio. They may not be exactly what you're looking for, but I'd definitely recommend giving them a listen if you're on the fence. They can be had for $299.95.
The most important thing to note about the performance is the lack of a completely flat frequency response. This will appeal to some who find really high notes and resonances to be painful in loud music, but maybe not so much to users who demand all sounds to be at the same volume as others. You can easily equalize these underemphases away, but it does require a bit of work on your end.

Beyond that, though, these headphones really don't present with many notable foibles: the distortion is well below audible limits, the tracking isn't perfect (but acceptable), and there aren't really any resonance or decay problems. The ATH-AD900x will more or less reproduce sound exactly how you want them to, but it's valuable to explore just exactly how this is so, even if it's only to satisfy your curiosity.

Well, that's certainly a chart—It'll be replaced in the future with a new aesthetic. For now, there are three features to note that are important: the underemphases in 2-4kHz, 5-7kHz, and the rolloff in the lowest frequencies.

These ~10dB underemphases are enough to make those sounds be half as loud perceptually than the rest of your music.

Per the underemphasis in the chart, these are ranges where the highest octave of a piano lives, as well as some of the sibilance of cymbals and the human voice (think /s/, /sh/, /f/ sounds). Like I said before, this can be mostly equalized away, but it does take some effort and know-how if you want to correct for this. However, if you often find those sounds to be annoying or painful in your music, you might elect to leave it alone, as these ~10dB underemphases are enough to make those sounds be half as loud perceptually than the rest of your music. It's something to think about, anyway.

In the low frequencies, we also see a general decline in volume from 80Hz down to 20Hz, starting at 72.5dB and gradually making its way down to about 60dB, making the lowest of the low sounds (which you may not be able to hear) less than 1/4th as loud as they "should" be perceptually. To make matters a bit worse, the human ear has more trouble registering low-frequency sound, so it typically needs to be louder than the rest of your music to appear at the same volume as the rest of the notes. If you're interested in this phenomenon, read up on equal-loudness contours.
By all our measurements, there was a small amount of distortion, but certainly none that was eminently audible. In terms of Total Harmonic Distortion (THD), the ATH-AD900x doesn't change your music too much, and you shouldn't notice any distortion unless you really crank it to 118.1dB, which is a dangerous listening level for any extended period of time. If you keep your volume at a reasonable level, you'll never have to worry about THD, despite the errant peaks that reach near 1%. Distortion peaks in lowest-end frequencies, but—as you may have guessed—is extremely hard to actually hear, as it happens in bass tones. Shouldn't be all that worried about the distortion peaking at 6% near 30Hz.

Switching gears to Perceptual Harmonic Distortion, here too we see a completely inaudible level, the worst of it hitting 1.35phon. Any way you slice it, these are some relatively low distortion cans, as you'd expect from not only their price point, but pedigree. No letdowns here.

Here we see a quick decay in the impulse, meaning there are few if any echoes when there shouldn't be. Most of the power is lost before 1ms passes, and continues out to about 3ms, which is well below the threshold of human audibility. If you hear a problem here, either your headphones are defective, or there's something in your music's mix that's causing it.

If you hear a ringing or slow decay, it's in your music, not the fault of the headphones.

So where is that ringing coming from? From the chart, it appears as though the worst of it is coming from that peak near 10kHz, but the cumulative spectral decay I recorded in a lab environment is actually quite good: the most prominent error only rings for an extra millisecond or two. Honestly, human ears are not going to hear that, and you shouldn't read into it that much. If you hear a ringing or slow decay, it's in the mix of your music, and not the fault of the headphones.

It doesn't look it, but the ATH-AD900x has some fairly good tracking here: It stays within about 2dB of channel preference. Even though that's not entirely ideal, it's inaudible at reasonable volumes, so there should be no perceptible issue here.

Meet the testers

Chris Thomas

Chris Thomas

Staff Writer, Imaging

@cthomas8888

A seasoned writer and professional photographer, Chris reviews cameras, headphones, smartphones, laptops, and lenses. Educated in Political Science and Linguistics, Chris can often be found building a robot army, snowboarding, or getting ink.

See all of Chris Thomas's reviews
Chris Thomas

Chris Thomas

Staff Writer, Imaging

@cthomas8888

A seasoned writer and professional photographer, Chris reviews cameras, headphones, smartphones, laptops, and lenses. Educated in Political Science and Linguistics, Chris can often be found building a robot army, snowboarding, or getting ink.

See all of Chris Thomas's reviews

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