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Grell Audio OAE2 Review

Petros LaskisUpdated October 23, 202611 Mins read3

Today’s review is about the OAE2, Axel Grell’s second headphone released under his privately owned brand, Grell Audio. Building on the same principles as the OAE1, the OAE2 introduces a revised tuning and improved ergonomics.

The review sample was kindly provided free of charge in exchange for an honest review. I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links.

The price of the OAE2 is $599 or €499 and is available from specialist retailers around the world. Click here to find the one nearest you.

Grell Audio

Grell Audio was founded in 2022 by the legendary audio and headphone engineer Axel Grell, the man behind some of the most famous and best-selling headphones ever made, including the Sennheiser HD580 Precision, HD600, HD650 and HD800/HD800S. Founding his own brand was a natural next step, giving him the freedom to express his creativity without the constraints of marketing.

Grell Audio OAE2

The brand’s first headphone, the OAE1, was produced in collaboration with Drop, which is now out of business. This is why for their second installment, Grell Audio was forced to take full responsibility of production and logistics.

The OAE1 became a huge success but was also criticized, mainly for its mediocre ergonomics and, secondly, for its enthusiast V-shaped tuning. The OAE2 is built using the same core engineering principles, but it features a different tuning and much-improved ergonomics.

I know that most people don’t like to read extended technical descriptions, but in the case of the OAE2 it is necessary in order to explain and understand the special technology that makes it unique. Feel free to skip directly to the user experience and listening impressions sections.

Grell’s Front-sided Sound Field Modulation (FSFM)

Both the OAE1 and OAE2 are unique because, unlike other headphones, they are tuned using Grell’s Front-sided Sound Field Modulation (FSFM) innovative technology.

When listening to a live performance or sitting in front of a pair of stereo loudspeakers, human hearing naturally processes sound arriving from the front. Traditional headphone designs inherently bypass this natural mechanism because they place transducers directly parallel to the ears, creating an artificial sound field that ignores the ear’s anatomical design.

In the OAE series, Grell introduces the Front-sided Sound Field Modulation (FSFM) technology, engineered to bridge the gap between traditional headphone driver placement and natural auditory perception.

Instead of blasting sound directly into the ear canal from the side, as it usually happens, Grell’s FSFM angles the transducers specifically in front of the listener’s ears. This front-angled projection mimics the wave propagation of real-world sound sources and stereo speaker setups.

By projecting sound waves from the front, FSFM forces incoming audio to interact naturally with the listener’s unique outer ear geometry before reaching the eardrum, enhancing sound-stage perception and improving resolution without resorting to artificial treble emphasis.

Other Technical Innovations

Among other things, the Grell Audio OAE2 incorporates carefully selected components made from high-quality damping materials, including plastics, zinc, and stainless steel.

An acoustically transparent stainless steel mesh is also injection-molded into a delicate yet robust plastic dome. Together with the high-quality damping materials, the special geometry of the baffle is responsible for the OAE2’s unique openness.

Unlike conventional headphones, the OAE2 uses an angled transducer positioned at an angle to the baffle. Its 40 mm transducer features a bio-cellulose dome, allowing for a large radiating surface combined with high excursion.

The curved open area of the OAE2’s baffle is twice as large as that of comparable headphones. This design allows sound to spread naturally, without reflections from large, acoustically closed surfaces.

The baffle is covered with a precision-manufactured stainless steel mesh made in Germany, which defines the acoustic impedance.

All these innovative technologies were developed in collaboration with the IKT institute at Leibniz University Hannover (Institute for Communication Technology).

Design and Build Quality

The OAE2 is a well-made and assembled headphone that doesn’t make any noises during use, and its durability inspires long-term confidence. The ear cups and the headband’s sliding mechanism are made from metal alloys. The only visible plastic parts are the two cable sockets, which are essentially extensions of the internal plastic-moulded dome.

It has a visually appealing, modern industrial design and looks like a premium flagship model rather than a mid-range $599 headphone.

The headphone is designed with sustainability in mind, so all components are user-replaceable and available as spare parts. The headband consists of two separately replaceable components. The lower, suede-covered section provides comfort, while the upper part is made from durable synthetic leather.

The ear pads are also user-replaceable and should only be replaced with the original ones, as they are an acoustically active component of the headphone. Other specialised parts, such as the headband mechanism, are available upon special request.

Improved Ergonomics

Grell Audio paid special attention to user feedback regarding complaints about the OAE1 ergonomics and has significantly improved everything in the OAE2.

The headband width has been increased from about 2.5cm to 3.5cm, and it has been divided into two sections. The lower part that touches the head is made from soft suede, while the upper part is made from durable synthetic leather. The whole headband is padded with soft foam, and there is an additional inner cavity at the center, filled with memory foam, which helps distribute the headphone’s weight and minimise pressure.

The length of the sliding rods has been increased from about 6.5cm to 7.5cm, allowing the headphone to accommodate larger heads. The original OAE1 barely fitted my head, but the OAE2 now fits well with a little extra margin.

The diameter of the ear pads has been increased from 5.5cm to 6.5cm, providing more space for the ears. The inner filing material of the pads is quite stiff, so they are a little less comfortable than other options with soft memory foam, but they help keep the headphone stable at the head. Moreover, the overall clamping force has been reduced from 3N to 2.5N and the weight is as low as 378g, which is not much for a headphone and is similar to that of many other models.

Wearing Experience

All these improvements translate into a headphone that is comfortable to wear for hours. The thick ear pads might cause a little sweating after a while, but this is normal with all headphones, and the centre part of the headband may feel just a little uncomfortable after a couple of hours. Otherwise, the OAE2 has solved all the ergonomic issues of its predecessor and is now suitable for extended listening sessions. As you have probably guessed, the OAE2 doesn’t provide any kind of noise isolation.

Stock Cable and Accessories

The headphone is equipped with two 2.5mm TRRS sockets and fully balanced internal wiring, allowing it to accept both single and dual entry cables. The package includes two 1.8m silver-plated OFC cables, one with a 4.4mm balanced plug and the other with a 3.5mm plug, plus a 3.5mm to 6.35mm adapter.

The stock cables are single-entry and can be connected to either the left or right socket. Other lengths and plug options, as well as, dual entry cables are available from Grell Audio’s website. Something worth noting is that the plastic cable socket is elongated, and when the cable is fully inserted and locked in place, its cotton outer sheathing rubs against the sockets’ sharp edge, with the risk of being damaged over time at this point.

Apart from the cables, the package also includes a hard carrying case for additional protection during transport. It is finished in synthetic leather and has enough interior space to accommodate up to three cables or a USB DAC dongle.

Impedance Rating and Power Requirements

With a nominal impedance of 38Ω and a sensitivity of 100dB/1kHz at 1VRMS, the OAE2 is an easy-to-drive headphone that needs only 1V to get really loud. So, in theory, even a simple USB DAC dongle should be enough to do the job. And indeed, the portable DAC/amps I have tested, such as the Cayin RU3 and the Shanling UA7, were more than sufficient.

However, for some unexplained reason, I felt that the OAE2 sounded “right” and that I was getting the most out of it only with considerably more powerful sources, like the iFi iDSD GR 2 or the iBasso DX340, or even better, with desktop components like the Aune N7.

I am not saying that it needed all that power to play music. After all, 500mW is the maximum power that it can handle. But I liked it much more from such sources. It might be just my idea or some placebo effect, so you are welcome to explore and share your findings in the comments below.

Listening Impressions

After the rather unconventional tuning of the OAE1, Axel Grell decided to return to the beaten track of absolute neutrality. The tuning of the OAE2 is almost perfect by critical-reference standards, with class-leading tonal balance throughout the entire frequency range. It is one of the best-tuned headphones I have ever tested, paying equal respect to everything from the deepest lows to the highest treble.

The sub-bass extension is surprisingly good for an open-back headphone, leaving nothing to be desired when reproducing the whole first octave without any kind of emphasis or roll-off, which is exactly what one should expect from a reference headphone.

The same principle dictates the tuning of the entire low-end, where no part is given undue emphasis that could spoil the tonal balance or color the sound. The OAE2 ensures that every single low-pitched instrument sounds as natural and correct as possible. From the double bass and the pipe organ to the cello, and even the lower harmonics of the viola and the bassoon, everything sounds absolutely realistic and precise.

Needless to say, the OAE2 excels at reproducing classical and acoustic music, but it can also easily handle all other bass-heavy tunes. However, don’t expect a cinematic, earth-shattering listening experience. This headphone is all about precision rather than any capricious attitude.

Technical but not Monotonous

The technical performance is also stellar. The very competent OAE2 reproduces bass with the precision and definition of a high-quality planar driver, while at the same time delivering the body, elasticity, and weight of a skillful dynamic driver. Fast, tight, and controlled, the bass is layered, well-defined, and crystal clear, without a hint of distortion or any audible cup resonances. It can keep up with the most demanding material you can think of, while still sounding dynamic, impactful and visceral enough. On a scale of ten, I would award the low-end performance of the Grell Audio OAE2 an eleven.

More Listening impressions

The transition to the mids is seamless, with the upper bass naturally leading into the lower mids, blending together in a natural manner without sounding disjointed. The mid-range follows the same neutral pattern that was established in the low-end. It is tonally balanced, accurate and present, without any kind of recession or artificial emphasis in the upper mids. Transparent and precise would be the words to use, as the OAE2 will reproduce what is in the source and the recording with disciplined fidelity.

Such tuning can sometimes lead to clinical sterility and boring flatness, but this is not the case here. The OAE2 sounds harmonious and very engaging with all kinds of music, as long as the source permits. Nothing gets added, but nothing gets subtracted either. Just use the source to steer the presentation the way you like. The textures are very refined, clean and well-defined, but also full-bodied and rich. The notes have plenty of weight to them, and the whole presentation is highly convincing and lifelike.

The treble is the part of the frequency range where things start to deviate from reference neutrality, as it is mildly emphasized and sparkling. You can’t call it bright or sharp, but it is not smooth or mild either. The OAE2 doesn’t sound piercing or fatiguing, but the truth is that it has an unforgiving nature that will not do any favors to poorly mastered recordings. It will also not pair very well with bright sources, unless this is your cup of tea.

Resolution but not Analysis

The headphone is very resolving and revealing, but it doesn’t sound analytical or magnifying like the Sennheiser HD800/S. Another key difference with this legendary headphone is that the timbre of the OAE2 is considerably more natural, without any metallic artificiality in the higher frequencies. I find the tuning a lot more mature and holistic, much more convincing and realistic, especially in the treble.

I know that I may upset a lot of people, but I have always thought that the HD800/S was out of tune in the higher frequencies. Impressive at first listen, but losing credibility after attentive listening. This is something that has been fixed in the OAE2, which might not sound as luminous and imposing at first, but after a while, you start to realize just how well and correctly it is tuned.

Oh… the Soundstage

If you were expecting the OAE2 to sound like speakers in your room, I am going to disappoint you. Let’s be honest, no headphone will ever sound like speakers, no matter how advanced it is or even with DSP applied. However, the OAE2 manages a unique sound projection that differs from all other headphones.

You don’t just get an open and spacious soundstage, as happens with other high-quality headphones that are known for having these abilities. With the OAE2, you get the extra feeling that the sound is radiating from a hemisphere-like source at the front of your head. It is not just the classical headphone-like soundstage that horizontally extends from left to right and also has some depth layering.

It is something more, a holographically arranged stage with realistic dimensions and precise positioning of the various sound elements inside it, both vertically and horizontally. It reminds me of an ancient Greek open theatre, where I am sitting in the orchestra and the musicians in the audience seating area. I don’t know how else to describe it. I can only add that the stage is very atmospheric and lifelike, especially with live recordings, and it really gives you the illusion that you are not just listening to headphones, but to high quality near-field monitors.

Vs the Competition

I am not going to engage in detailed side-by-side comparisons with other headphones. What I want to highlight in this section is that the OAE2 offers class-leading tonal accuracy that the usual suspects, like the Sennheiser HD650, HD660S2, and HD800, can’t really match. The same applies to many planar magnetic headphones that tend to sound too bright, as well as the Focal Clear/Mg, which sounds slightly out of tune in comparison.

I am not suggesting that the OAE2 is the only tonally correct headphone in this category. The Neumann NDH30 and the HEDDPhone D1 immediately spring to mind as very worthy competitors. However, the OAE2 is the only one that combines this level of tonal accuracy with such a unique out-of-the-head, speaker-like presentation. You are not necessarily going to like it, but if you do, it will be really difficult to return to regular headphone listening.

One last point worth mentioning is that you shouldn’t let the price of the Grell Audio OAE2 fool you, as it doesn’t sound like a mid-range headphone to me. It can easily compete with the Sennheiser HD800, the Focal Clear Mg, and the Hifiman HE1000. There are differences, of course. It doesn’t sound as analytical or energetic as the Sennheiser and the Hifiman, nor does it punch as hard as the Focal, but it has many other virtues that allow it to look them straight in the eyes.

In the End

The Grell Audio OAE2 is a revolutionary headphone that projects sound in a very unique way that could be said to resemble near-field monitors. It also has reference tonal accuracy, is considerably more comfortable and ergonomic than the OAE1, and is very well made and fully serviceable.

Its class-leading sonic performance not only makes it one of the best offerings in its price category but also allows it to compete directly with much more expensive headphones. Speaker-like or not, the Grell Audio OAE2 is one of the best-tuned headphones for anyone looking for neutrality without sacrificing musicality, and one of the best options regardless of price.

I would even go as far as to argue that the OAE2 is, generally speaking, better than the Sennheiser HD800/S, at least for me, and is the kind of successor that many headphone enthusiasts have been waiting for.

Test Playlist

Authored by Petros Laskis for Ichos Reviews. All content is original and copyrighted. Republishing full reviews or portions without written permission is prohibited. Excerpts up to 100 words are allowed with a direct link.