Audeze has claimed their position in the upper echelon of the headphone industry, which is quite remarkable considering the relatively brief timespan in which they forged their reputation. Their landmark LCD-2 headphone not only swiftly stole the hearts of a large following, but managed to evolve into a universal reference point for smooth, natural sound. When asked what kind of sound you like, “I’m an Audeze kind of guy” is considered an appropriate response, especially when used as counterpart for the brighter, more analytically-oriented HD800.
All of their headphones of course solely uses planar technology, which comes with its own set of advantages. For instance, as their drivers consist of an ultra-thin diaphragm, it allows them to provide a rapidly quick transient response; i.e., the ability to follow dynamic changes in the music with high precision, as well as offering high transparency. And of course, the renowned planar bass by itself has become a primary reason for Audeze’s loyal fanbase.
Audeze’s increasing experience with planar technology drove them to a new challenge: fitting a planar driver into an in-ear format – an LCD headphone in ‘fun-size’, if you will. An ambitious project, resulting in some long overdue innovation in the in-ear market. Even so, resizing the driver came with challenges of its own, especially when tuning the sound. Traditional BA designs consist of specific drivers that are chosen for their sonic properties, and subsequently linked together with a crossover to achieve the desired sound.
But due to the i4’s novel technology, the tuning process, and following end result, was a little bit different. Specifically, the i4 wasn’t tuned for either low distortion or a certain signature, but to simply optimize the performance of the driver. For instance, by varying the width of the traces in the diaphragm, Audeze managed to achieve a uniform electro-magnetic force across the diaphragm, which is deemed important for absolute control and a linear response.
So in a way, the signature followed from its physical design, rather than the other way around. In addition, an over-ear headphone uses human anatomy (the curvature of the outer ear) to boost the midrange frequencies, which is not possible with an in-ear design. Therefore, Audeze experimented with the shape of the ear port and size of the opening, as well as different materials for the golden mesh, while using using wave guides inside the sound port to fine tune the sound. But they also sought out an alternative angle: providing DSP correction via plugin or their Cipher cable to modify the frequency response without using EQ.
The i4 is a unique piece of equipment; not only due to its planar driver, but its open-back design. One could argue it’s equal parts ‘clip-on headphone’, in-ear monitor, and more generally speaking: technological gadget. Its quirky over-ear design and matte black plastic with golden indents has a retro look, which seems to resemble an ode to how people in the 80’s imagined products in the future would look like; at least, that’s my personal interpretation of it. The design certainly has its appeal, although it might not be universally acclaimed.
This returns in its usability. While the i4’s project the sound in the inner ear, the outer shells containing the driver are placed against the ear. Audeze provides a selection of different hooks to keep them in place, which are easy and practical to use. Despite their size, the overall body does not feel heavy while wearing, although it might take some time to adjust the angle of the nozzle. But the most striking difference with a contemporary in-ear follows from its open-back design, which allows ambient sound to flow freely through its open port.
As a result, the i4 is exceptionally susceptible to outside noise, especially when compared to the tight seal of custom in-ears. Admittedly, I was initially taken aback when walking outside while listening, although I later started to appreciate the way the ambient sound grounds you in the surrounding. However, it should be noted that the i4 is probably best used indoors to fully be enveloped in the music.
There’s something unique about the way the i4 presents its music. It’s not necessarily due to the macro elements of its sound: the natural quality of the bass, the body of its midrange, or even its stage dimensions, that inevitably seem to stretch just a bit further than its peers, bound by their contemporary multi-BA design. It’s woven in the finer building blocks of its sound – fleeting upon initial listen, but impressive on further acquaintance: the ethereal decay of its treble, the quick transient response with which it follows fast guitar riffs, and the sense of realism following its high definition and precise imaging; all subtle variations throughout its presentation, revealing there’s something special driving the sound.
But even more striking, though equally subtle in its execution, is the soft articulation with which the i4 presents the music; as if handing each note with a velvet glove. While traits as smoothness and articulation generally result from the treble tuning, the i4’s articulation results from an inherently different type of sound waves, contrasting the more aggressive attack of balanced armatures and dynamic drivers – a faint note that seals the unique presentation of the i4.
But the i4’s greatest feat perhaps is the way it manages to balance the naturalness of its timbre, with the clarity of its treble. A treble that’s not only rapidly quick, but detailed and clear, with an almost pristine quality. Yet despite a rather melodious-sounding lower treble, it refrains from being over-accentuated and bright. Rather, the clarity resides in the way the overtones light up the stage; there’s a true sense of openness and light in its presentation, and purity in its sound.
The midrange equally, is a region where the i4 shines. Or more precisely, can shine. Admittedly, the i4 initially greets you with a somewhat laid-back midrange, resulting in distant vocals, which affect their transparency – subtle tells, hinting at a significant dip throughout its midrange. Its tone in turn is clear, and thoroughly neutral. A versatile sound, that readily lends itself to adapt to different genres. Yet simultaneously, something feels amiss – a touch of warmth in its midrange, for the accuracy of its timbre.
While inevitably present, achieving the i4’s complete potential tends to require some additional steps. Not unlike a seductive vixen playing hard to get, the i4 makes you work for perfection – for those that persist, the reward is there. Practically, this entails just a bit of effort to tweak its sound. The easiest route is via Audeze’s included Cipher cable, with built-in DSP correction. The most rewarding however, is by using Audeze’s DSP presets on a desktop system or USB DAC, or alternatively, by manually adjusting EQ on a DAP.
The DSP adjustments aren’t designed to transform the i4’s sound to something different altogether; in fact, some might argue they aren’t a necessity at all. The settings consist of a set of modifications to fine-tune the sound, primarily targeting the midrange specifically. When implemented, the i4’s vocal position is no longer distant, but centered within its three-dimensional stage. The i4 doesn’t necessarily put vocals in the spotlight, but creates a sufficiently dense vocal for them to sound engaging; a solidified, and pleasantly bodied vocal.
By doing so, the i4 constructs an egalitarian approach between its vocals and instruments, emphasizing neither over the other in terms of forwardness or body. But more importantly perhaps is the provisional touch of warmth in its midrange, essential for the naturalness of the sound. While the i4 retains the crystalline quality of its treble, detailed, with a friendly touch of sparkle, the midrange now sounds slightly warm, with a beautiful timbre.
For many, the entrée of renowned planar bass in iem form might be one of its true highlights. Indeed, the i4’s bass is bliss for aficionados that appreciate finer nuances that constitute quality bass. It combines the extension and sub-bass impact of a dynamic driver, with the speed and airiness of a balanced armature – topped off with a unique texture of its own. By maintaining a linear response throughout its lower frequencies, the i4 finds a delicate balance between naturalness in delivery, and capable technical reproduction. Accordingly, it provides a deep impact when required, while remaining eerily natural in tone. A lightly warm bass, with a softer touch – a refined bass presentation, more than anything; and one that always stays perfectly coherent within the rest of the presentation.
And more importantly, a perfectly controlled bass, ensuring the airiness of the stage: the i4’s final feat. In overall dimensions, the i4 constructs a spacious, three-dimensional image, with even proportions between width and depth. It’s an especially airy stage, resulting in an open feel that allows detail to emerge in effortless manner. But where it departs from its more contemporary competitors is not primarily in its overall dimensions, but its use of space. The i4 not only positions instruments in layers towards the rear, but varies in its placement in height – effectively making more avail of the total space. Combined with a keen sense of imaging, the i4 conveys a more tangible feel of three-dimensionality.
The i4’s most optimal use is when listened via a USB DAC or desktop system, with the provided DSP settings. However, when listened directly via a DAP the EQ can be manually adjusted by ear to approach Audeze’s target curve. However, it remains a bit tricky to get the tone exactly right. So surprisingly, one of the best pairings is by simply using an iPhone with the Cipher cable. The i4’s stage might not be as large as with a high quality dap, but the timbre is just right. It offers the same clear sound, but a warmer tone in the midrange makes for more natural vocals and a significantly more accurate timbre, while still offering a clear and highly detailed treble.
When using a DAP, the i4 tends to have an exceedingly neutral tonality. It’s not necessarily bright, but the midrange isn’t inherently warm either. In addition, its vocal presentation is relatively laid-back, although this can simply be adjusted with EQ. For instance, the Lotoo Paw Gold is a personal favorite as its bodied vocal reproduction creates a solidified, forward sound, while adding a sense of energy throughout its signature. However, I EQ the mid- to upper-treble region down in order to create a smoother sound, with a more natural timbre.
By comparison, my modded Sony WM1Z provides a powerful bass with a neutral tonality that fairs well with the i4’s sense of space and precision, although I tend to EQ a little more in the midrange for vocal density. By contrast, it’s more difficult to achieve a sense of naturalness in its midrange. Though not excessively warm, both the A&Ultima SP1000 Cu and AK380cu handle upper treble smoothly, adding a lightly warm and smooth touch to the i4’s clear sound, while maintaining a relatively neutral tonality. I found the pairing with either to be among the best, followed by the LPG.
Spiral Ear 5-Way Ultimate (€1799)
A long-standing icon for timbre, the 5-Way impresses with its resolution and staging, in defiance of its warm and soothing tone. Exceeding naturalness as a priority, but within a bigger picture. Yet despite their difference in technology and even tonality, the 5-Way and i4 aren’t miles apart when it comes to the core of their presentation: a three-dimensional stage, with a neutral instrument placement in terms of forwardness. And more importantly, both iems depict their own interpretation of naturalness. The i4 creates a realistic representation of its instruments by means of its high definition, and quick transient response, and the 5-Way with its overall warmer timbre.
Down low, they converge with natural-sounding and technically capable bass, albeit in different interpretations. Both offer good bottom-end extension, with capable speed and decay, while hovering around neutral in overall quantity. But the 5-Way’s bass is significantly warmer in tone, where the i4 maintains a similar sense of naturalness, with a lighter tone. And while they share similarities in the density and forwardness of their vocals, the 5-Way’s are just a bit more bodied, and warmer in tone. But their greatest difference perhaps is in their treble tuning, with the i4 offering greater clarity throughout its signature, besides a more neutral in tone. Its treble is not only quicker, but clearer, resulting in a greater sense of detail. This returns in the way they construct their stage; while the 5-Way offers a spacious, three-dimensional stage, it can’t match the airiness and following openness of the i4.
Empire Ears Legend-X ($2399)
How different with the Legend-X, Empire’s recent addition boasting two dynamic drivers in a hybrid configuration. Its forward treble gives it an energetic, but also slightly aggressive, character. Bolstered by its powerful bass, the Legend is a young gun that can’t contain its excitement. Compared to the Legend, the i4 eludes a sense of calmness and wisdom; a more mature presentation. The i4 has the more natural bass, lightly warm, and exquisitely balanced between sub- and upper-bass. A delicately refined bass, that does a lot of things right. The Legend’s bass wasn’t tuned for balance; it was tuned for power – a deep, rumbling bass with emphasis on its sub-bass, and clarity in its impact.
Even so, both are surprising close in tone, boasting a generally neutral tonality. An overall clear sound, without sounding bright. However, after DSP correction the i4 offers the more natural midrange, with a relatively more accurate timbre. The Legend-X’s signature in turn diverges with more sparkle in its upper treble. While both create a bodied sound, the i4’s vocals are smoother, while exuding greater balance. In addition, the i4’s stage is more homogenous in proportions, as well as airier; that aforementioned bass has consequences of its own. Accordingly, the i4’s presentation is cleaner, resulting in more effortless separation. While offering sufficient depth, the Legend’s stage is primarily wide, with a more forward placement.
Vision Ears VE8 (€2399)
Although inherently different in a variety of aspects, the i4 and VE8 equally share several general characteristics. For starters, both have a relatively neutral tone, and an overall smooth and engaging presentation. The VE8 by means of its forward staging and bodied midrange, while the i4 envelops the listener with its balanced presentation, and holographic stage. While the VE8 equally offers a spacious stage, it primarily relies on its width for its separation. In addition, the VE8 offers a smoother tone with a modest touch of sparkle, while the i4’s treble sounds just a bit crisper.
The VE8’s bodied sound partially stems from its enhanced mid- and upper-bass. It’s an engaging bass, although its emphasis resides on the upper registers. It’s not a boomy bass by any means, but its impact follows from its mid-bass body, rather than its sub-bass power. The i4’s bass in turn provides deeper extension, with greater balance between the sub- and mid-bass. A bass that allows it to provide a nice touch of impact upon request, while remaining neutral in quantity, and airy in its approach.
The i4 is, without a doubt, the most unique earphone I have reviewed till date – and admittedly, the reason it took a while to write up. The unique properties of its planar driver, open back design, and various adjustment options set it apart from contemporary iems, resulting in a unique listening experience, combined with some practical constraints. In a way, the i4 is almost equal parts high-end in-ear, and high-tech gadget. And just like when discovering any new technological advancement, it tends to require some playing around to get right.
In the case of the i4, it’s by experimenting with DSP and manual EQ. Of course, the i4 doesn’t ‘need’ EQ to sound good. Audeze’s DSP settings aren’t intended to alter the foundation of its sound, such as its tone or staging capabilities. Rather, the presets help to adjust the vocal reproduction, by enhancing the density and forwardness of the vocal range, while simultaneously improving its timbre.
For those willing to invest some time and effort, there are exclusive benefits to reap. For starters, the i4’s natural portrayal of sound. This doesn’t just refer to its tonality, but the way it presents the music: the realistic use of space, its transient response, and the delicate flow of the music. And most importantly, the contrast between the clarity of its treble with a beautiful midrange, matched by the naturalness of its bass. A spacious and open sound, employing the full advantage of its special driver.