AKG K371 Review - Closed-back Benchmark Headphone

Review written by @Chrono

Introduction

The AKG K371 ($149 MSRP) is a closed-back, over-ear headphone designed by AKG intended for studio use and audiophile listening. In the last decade or so, the Harman Audio Group (AKG’s parent company) has been researching and defining the “optimal” frequency response that–when measured at the ear-drum–results in a tonality that is the most preferable and natural-sounding to the majority headphone listeners. The frequency response that was borne of this research is what has come to be known as the “Harman Curve,” and it is the tuning that defines the AKG K371’s tonality.

Sources and Music Used in Listening Tests

The Amplifier/DAC used in this review was the iFi iDSD Micro Black Label connected via USB to my desktop computer. For the listening tests I used music from a wide variety of genres including Rock, Jazz, Classical, Acoustic, Hip-Hop, and latin. I played tracks from my own FLAC library as well as from Qobuz streaming service. 

What’s in the Box?

For its $149 price tag, the AKG K371 includes a very nice suite of accessories. Included in the box are three 3.5mm to mini XLR cables of varying lengths. The first set of cables are both straight, and measure 1.2m and 3m in length. The third cable also measures 3m in length, but is coiled instead. Also included are a thread-on ¼” adapter as well as an AKG-branded, grey carrying bag.

Power Requirements

The K371 is a very efficient headphone at an impedance of 32ohms and a sensitivity level of 114dB (edit: 114dB/V and ~99dB/mw). It did not matter what device I was running it from or whether or not I used an amp; it sounded great on everything I tested it on, so I will not be listing a discrete headphone amplifier as a requirement. 

Build Quality and Comfort

The build on the AKG K371 is for the most part very good, but there are some parts on it of which longevity I am slightly concerned about. The K371’s design is very compact and has a foldable ear cup mechanism that makes them easy to carry on-the-go. The build is composed almost entirely out of plastic, but it feels very solid and well put together; I don’t think that it will start to creak or break any time soon. The pads are made of a very nice pleather material that I do not seem prone to flaking, so they should also last a while. The parts that concern me are the inner headband and extension mechanism. The inner headband is made of rubber, and it seems to be glued on to the top. This worries me a little because I think that the rubber pad might start to peel off some time down the line, and it is something I have seen happen often on headphones sharing a similar headband design. Additionally, the headband expansion mechanism does not lock very tightly at each click, so I fear that over time it will start to get very loose.

Comfort is surprisingly good considering the relatively-small footprint of the K371. As a closed-back these isolated sounds quite nicely, and did leak much of the music out even at loud listening levels. The pads use a very light foam, and provide a pretty decent amount of room for your ears to fit in. Occasionally I did feel as though my ears lightly touched the driver, but it was not really all that noticeable. My only complaint for the comfort was that the clamp force out of the box was a little on the tighter side. However, they did ease up nicely after using them for a day or two.

Sound

As mentioned earlier, the AKG K371 is tuned to match the Harman Curve Frequency response target, and it does so almost perfectly. When measured, the AKG K371 measures essentially flat or “neutral” when its frequency response is compensated for the 2018 over-ear Harman Curve Target. My preferred tonal balance is very similar to that suggested by the Harman Curve, minus a few deviations that I will mention as we discuss the K371’s sound. As a result of their adherence to the Harman Curve, I personally find the K371 to be one of the most tonally-appropriate headphones I have listened to; and according to Harman’s research, that is also likely the case for most headphone listeners. However, tonality is not the only element in a headphone’s performance, let’s take a closer look at how the K371 performs.

NOTE: These headphones are intended for professional audio usage. Professional audio is an area I do not have experience in, so I am unable to comment on how they perform in studio or mixing applications. All comments made in this review pertain to my experience as someone who is listening to them solely for personal enjoyment.

Bass

The K371, to me, has one of the best bass tunings of any headphone I have tried in the sub $200 price range. The bass extends very evenly down to 20hz, and it has a Harman-style up-shelf starting at around 100hz that gives the sub-bass a good level of presence. The only quirk I found with the K371’s bass is that it seems to have a very small bump at around 20hz or 30hz, but aside from that it did not have any strange mib-bass bloats, or upper bass bleed into the lower mids. For resolution, I found the K371’s bass to have a good level of articulation and I think that it was appropriate for the price that these retail for. Of the closed-back headphones in its price range, I only found the DT 770 Pro to be a slightly more detailed. Overall, I find the bass on these to be very clean, and enjoyable; this is a great option if you are looking for an affordable closed-back with deep and balanced bass.

Mids

The K371’s midrange is–like the bass–very good. They have a good amount of body in the lower mids, as well as an adequate amount of presence in the region between 2k-5k. Comparing back and forth with the HD 660S and HD 58X, I found the mids on the K371 to be very similar in their tonality and timbre to that of the Sennheiser’s; they have a very good balance and sound very natural to me. Resolution I think is fine for $149, although they did come across as a little bit grainier to me when compared with the ATH-M50X and DT 770 Pro in the midrange. Still, I personally preferred the midrange’s tonality much more on the K371 when comparing with those other closed-backs.

Highs

The treble region is very good on the K371, and I find it very impressive for a closed-back under $200 to have this accurate of a tuning. The highs on the K371 lean towards a warmer tonality, and have a very good balance to them; they are for the most part very smooth. The only slight deviation I heard was that at around 8.5K there seemed to be a very narrow peak, but it was very subtle. I only noticed it when listening to songs that had inherently sharp treble, such as Oasis’ “Wonderwall,” or The Beatles’ “What Goes On.” For my preference, I would have liked for them to extend a bit more into the air region above 10K, but the Harman Curve does call for less energy in those upper-treble frequencies. Resolution in the treble I think is fine for the price, as it is on-par with the ATH-M50X and only slightly behind the DT 770 Pro.

Soundstage, Imaging, and Layering

In these categories, the K371 is definitely not the most impressive headphone out there, but it did perform very well for its price and when compared to some of its peers. For a closed-back, the soundstage is not actually that bad on the K371. I thought it had a decent level of width as it was similar to that of the HD 58X, which is an open-back. I also found it to have a much wider soundstage than the ATH-M50X, but not quite as wide as the DT 770 Pro which is astoundingly wide for closed-back under $200. Imaging was also fine, I didn’t really have any issues telling the direction from which sounds originated. In my experience, it seemed to image a bit better than the HD 58X, but definitely was not as precise as the DT 770. Instrument separation was also surprisingly good. I found it very easy to tell apart the different elements that made up the tracks in the music I listened to, and it seemed to do so significantly better than the DT 770 and ATH-M50X.

Dynamics

Unfortunately, I was a little underwhelmed by the dynamics on the K371 as they do not add as much energy and weight as I would have liked them to. It does not really have a strong punch and slam quality. Compared to some of the other headphones in its price range, like the DT 990 Pro, the K371 did not really deliver a deep and satisfying physical impact.

EQ

Of the headphones I have listened to, I think that this is the one that I feel the most confident when I say that it does not require EQ. Nonetheless, I have made an EQ profile for the K371 that brings it closer to my personal target (only personal preference change I made was reducing the bass sub 100hz), as well as reducing that slight peakyness at 8.5K. If you would like to try this EQ profile out, these are the settings that you can input in your equalization software of choice:

• Peak at 20hz, -2dB Q of 1.4
• Low Shelf at 100hz, -2dB Q of 0.7
• Peak at 8500hz, -4dB Q of 6

Conclusion

The K371 is a fantastic package that offers very good value and really hits all the marks that you would want in a closed-back headphone. The K371 has a versatile and enjoyable tonality, it offers competitive technical performance for the price, it’s easy to drive, it’s very portable, and it includes a plethora of accessories. At its price tag of $149 the AKG K371 has sincerely impressed me, and I think that–at least for tonality–it should be considered as a closed-back benchmark.

-Chrono

Check out the video review here:

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