[Listening test] IK Multimedia ARC ON.EAR

Product: ARC ON.EAR - headphone amp & DAC/DSP
Manufacturer: IK Multimedia - Italy
Approx. price: ±€300 (including VAT)
Reviewer: Lucio Cadeddu - TNT-Audio Italy
Reviewed: November, 2025

Foreword

It's time for a stunning 100% Italian product, that can convince even the most sceptical audiophiles that DSP-based technologies can truly change the face of this hobby. The ARC ON.EAR headphone amplifier that IK Multimedia gave me to test not only amplifies the signal for your headphones, but also realigns their frequency response via software. To do this, it relies on a vast database of frequency responses from around 200 headphones and applies the necessary corrections (calibration as they put it) to make them sound perfectly flat.

Before going into the details, because this little device does much more than that, a few words about who IK Multimedia is. In their own words, “We're innovators of guitar, recording, instruments, and audio creation technologies that make you sound better.” A Modena-based company that has been making components for musicians, sound engineers, and producers since 1996. Their catalogue is extensive, as you can see by browsing their website. They also have room acoustics correction software, which may be the subject of another review.

A closer look

We all know that the frequency response of any headphone, even the most expensive ones, is never perfectly linear. This is a problem not only for us simple listeners but also for those who work with headphones, such as sound engineers. These also need to be able to simulate the sound they would get in the studio with their monitors, so they can evaluate a master even when they're away from the recording studio.

These two needs are addressed by this little device, the ARC ON.EAR, a sort of magic box that, drawing on a vast database of approximately 200 frequency responses of existing headphones on the market (a database that is constantly updated), modifies the signal sent to the selected headphone so that the output compensates for the peaks and dips typical of that specific model. It can do this either by connecting it directly to a PC/notebook, thanks to which you can select the headphones in use (up to 5 different presets) or even by working stand-alone, connected to any external line source via the mini-jack input.

You can therefore connect a CD player, a streamer, a phone, a phono preamp, a digital source (via USB), etc. A convenient volume knob allows you to adjust the listening level. The unit has three switches that allow you to: activate/deactivate the calibration, select one of the 5 stored headphones (LEDs indicate the order of the pre-sets), but also activate MUTE or other functions and activate the studio mode, which simulates the audio of a control room, in which virtual speakers play, also selectable from a database of the most common studio monitors (Yamaha, Tannoy Dual Concentric, B&W, etc.). This last function is of little interest to an audiophile but essential for the professional.

The unit features a USB-C port for connecting to a computer, an external power supply, or a digital source, a power switch and LED, and a 6.3mm headphone jack. Power is provided by an internal battery (3.7V, 1200mAh) that allows it to operate unplugged for up to 4 hours.

Via software you can do much, much more: you can modify the equalizations with adjustments across three frequency bands, you can change the timbre setting of the calibration continuously from neutral to bright or warm, you can insert a phase correction, and you can modify the virtual sound environment, with speakers positioned differently in the virtual control room. The selectable speakers, which you simulate with headphones, are numerous and - as a sound engineer's logical requirement - you can even simulate sound-bars, TVs, and smartphones.

For us simple audiophiles, it's enough to select the headphones we're using (first check that they're included in the database!) and leave everything else flat, or maybe have some fun tweaking some calibration parameters. The software screen allows us to view both the headphone's original frequency response and the calibrated curve.

There's no need to install additional libraries or other tricks; the software is self-installing, and my MacBook Pro immediately recognized the ARC ON.EAR as an external audio device. I couldn't test it on Windows because I've removed that operating system from my life, relying solely on iOS and Linux.

The exact models of the chipsets which have been used aren't available: to see the other side of the motherboard, I would have had to disassemble the unit more brutally, so I decided not to. The company doesn't provide any further details beyond those listed below.

Claimed tech specs

Aladdin's Genie Lamp via DSP

Among the headphones I own, the ARC database includes both the top-of-the-line Grado Prestige series (the 325s) and the budget-friendly Superlux HD681 reviewed some time ago. I therefore had the opportunity to evaluate the calibration process on both high quality and budget headphones. I also tested the ARC ON.EAR as a pure headphone amplifier (with calibration off), comparing it to some of my budget-class references, including the iFi Zen Air Can.

Since the introduction above has been necessarily lengthy, to explain most of the capabilities offered by the component under review, I'll get straight to the point: the ARC ON.EAR works, and it works damn well. With both the Grado and the Superlux, the calibration process is evident and, I'd say, absolutely effective. Even the Grado 325s, which already sound very good out of the box, improve both in the mid-high range and a little in the bass range, without any loss of quality and without ever having the sensation of listening to something artificial.

Since you can turn calibration on and off at the touch of a switch, it's incredibly easy to understand what's happening to the sound. Sometimes, I admit, after getting used to calibrated listening, I struggled to recognize the sound of uncalibrated headphones; it seemed so much worse! So: the frequency response changes, for the better, but everything else remains unchanged. Dynamics, for example, remain the same, as do transparency and micro-detail.

It's clear that if calibration slightly increases the higher frequency range (perhaps because it's not flat with uncalibrated headphones), it will improve the detail and the amount of information extracted from the recording. Naturally, it can improve the impact of the bass range and its control. For example, the bass of the HD681, which has a small bump around 100 Hz, becomes less gummy and more natural. The mid-high range, which is sometimes a bit exuberant, becomes more pleasant. The device, at least with the headphones I tested, does not substantially change the headphones' ability to sound three-dimensional.

I know what you're thinking: but if the software realigns the frequency response of each headphone, then all the headphones will sound the same! Obviously not, and for a whole host of reasons, because the sound of an audio component is not determined solely by its frequency response! The bass response is still limited by the size of the diaphragm and its ability to keep track of signal variations for example. It would be like thinking that through digital manipulation you can make a 10cm woofer sound like a 20cm one, evidently you can't. The former, with the same excursion, moves less air. Furthermore, the distortion rate introduced by the diaphragm cannot be changed, so a cleaner headphone will continue to sound better than one that distorts more. Likewise, the ability of the diaphragm to follow the slightest variations in the signal remains the same, so - to be clear - the qualitative distance between the Grado 325 and the Superlux HD681 remains practically the same...they both simply improve, becoming more linear.

I couldn't detect any negative or artefactual effects, much to the chagrin of audiophiles who think DSP is the root of all evil. There are bad DSPs and good ones. This software calibration from the ARC ON.EAR works very well. Of course, if you love your headphones partly or primarily because they're non-linear, you might not like this frequency response realignment. It's well known that many audiophiles don't like knowing the truth, clinging to an idea of MyFi sound that doesn't actually exist. There's obviously no cure for these mental distortions. However, even the most ardent MyAudiophiles might be surprised to discover how much better their headphones can (and will!) sound.

Without listening with higher-quality headphone amplifiers, the limitations of the internal amplification aren't very noticeable, but they do exist. Comparing the uncalibrated headphones under review when amplified with the ARC ON.EAR and, for example, the iFi Zen Air Can, the advantage of the latter is quite evident, both in terms of power and depth of the bass range, and in terms of overall dynamics. This could be caused by the output power of the ARC ON.EAR's internal amplifier, which is certainly not exuberant (100mW versus the iFi's +1000mW), at least for me, as I'm used to listening to certain genres of music at high volume. With the Grados, the power output was sufficient; with the HD681s, I would have appreciated a few extra dB, especially since, reaching the maximum volume range, you can hear some strain and compression. I haven't been able to test high-impedance, low-sensitivity headphones; I imagine the result could be worse.

For this reason, I think it would be a good idea for the manufacturer to provide a calibrated line-level output, thus bypassing the internal amplification. I don't know if this is technically possible, but it would greatly expand the capabilities of this component. I can already imagine the objection: the calibration is performed based on the internal headphone amplifier and therefore it would sound out of calibration with an external amplifier. It's possible, but it would still be worth trying.

Used briefly - because it's beyond the scope of this review - as a recording studio simulator with different types of speakers, I have to say the ARC ON.EAR works equally well: it's fun to simulate different sound fields, with speakers spaced more or less far apart, angled, with or without additional ambience. There are many speaker models available; from the photo and name, you can identify the most commonly used monitors in recording studios. The exact make and model, I imagine for copyright reasons, are not disclosed. In short, for those who want to have fun making their own home recordings, there's plenty to enjoy.

Summarizing, even as a simple audiophile component, thus exploiting only a minimal amount of the device's potential, I consider this ARC ON.EAR and its software to be one of the most intelligent implementations of digital audio. The component is well built, simple to use, works very well and, I say it quietly, it is even too inexpensive, if I think about how much HiFi companies make us pay for certain empty and useless boxes. €300 (including VAT) for a simply fantastic software and a beautiful, portable, smart, and easy-to-use component is a price that speaks for itself. And it's even more so when you consider that it's all designed and made in Italy. These days, that's truly incredible.

Remarks & Complaints

Manufacturing & Finish.
The construction seems bombproof, the component is easy to use and can be carried in a pocket thanks to a nice case (it weighs 170 grams and fits in the palm of your hand!). It comes with all the necessary cables and can even be used on the go, without a power supply. To expand its capabilities a bit, I would like to see an RCA line input (in addition to the mini-jack) and the possibility of wireless connection via Bluetooth, which has become essential. I would expand the software's compatibility to Linux (for now only Mac and Windows) and consider an app, perhaps even a simplified one, for use on Android. A lossless streaming service on your smartphone, a pair of headphones, and ARC ON.EAR to calibrate and amplify everything could revolutionize headphone listening both indoors and outdoors. I would like to see an audiophile version of this component, without the whole virtual studio part that we don't need and, perhaps, with a better quality amplifier section that does full justice to the magic of the software.
Sound.
There's not much to say: it works damn well and can improve the sound of even good headphones. It won't turn a duckling into a swan, but it will certainly take it to another level. The quality of the amplifier section could be improved, but you can't expect the same level of performance from an external amplifier that costs half as much as this component, considering the things it does. In my opinion, the software alone is worth the asking price.

Conclusions

Many people ask me if reviewing HiFi products is always fun and rewarding. Not always, I assure you: sometimes it's boring, other times downright disheartening. However, for me, just encountering products like this every now and then is enough to rekindle my enthusiasm. Unfortunately, that happens all too rarely. The ARC ON.EAR gets full marks, finally something new that does what it promises at an absolutely affordable price and with a simply stellar quality/price ratio.

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IK Multimedia ARC ON.EAR - headphone amp, DAC & DSP

Aladdin's Genie Lamp via DSP

Foreword

A closer look

Claimed tech specs

Aladdin's Genie Lamp via DSP

Remarks & Complaints

Conclusions