Fit and Comfort

Seen above is the right channel of the 64 Audio Volür installed into an artificial ear mold, and I am using the size M black bore silicone ear tips included with the IEMs here. This was my typical combination for personal use too, and illustrates the nature of the achievable fit with these IEMs. I do have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. The ergonomic design of the shells shaped for the ear concha works out well for most ear types, especially given the smaller size of the shells compared to most IEMs on the market. In general, the gentle curves all around the shells make for at least two to three points of contact with the ear to help support and keep the IEMs in place. One thing to be aware of is the vent at the top—position the shells so it's not blocked, lest the bass response be affected. In general I'd say this is a non-issue given the placement of the vent and how it would naturally be directed away from the anti-tragus of your ear. The longer nozzle also results in the the ear tips go in far enough to make for a better fit and seal, although the company's modular Apex technology will ultimately decide how good the seal turns out to be. The nozzle being quite thin is also a plus point for those with smaller ear canals, and the Apex modules help make the Volür extremely comfortable over long listening sessions, as any built-up air pressure in the ear canals is released in a controlled fashion. As such, there is no sense of physical fatigue—the shells barely weigh 6 g each—with a good fit even if these aren't the most isolating IEMs. The angled connectors on the cable also worked quite well for me, but I can see the shell positioning for some resulting in the pre-formed ear hooks not immediately going over and behind the ears.

Audio Performance

Audio Hardware

Seen above is an exploded wireframe illustration to show the various components that come together to make the 64 Audio Volür. We do not get a lot of information about the exact drivers used although it is evident that the Volür uses a hybrid driver setup involving two dynamic driver and eight balanced armature drivers in a 4-way crossover. Those two dynamic drivers are already where things get interesting given 64 Audio is using a true isobaric configuration. What this entails is a cone-to-magnet—as seen in the second image—setup wherein the two drivers are connected to each other via an acoustically inert coupling chamber. One driver diaphragm is fully sealed off and it's only the other that contributes to SPL. Other such dual DD configurations can be push-pull (as with MOONDROP with its H.O.D.D.D.U.S driver seen in the Blessing 3 and Solis 2) or purportedly isobaric in that some claim as much but don't provide enough details or share some info that doesn't make sense. Regardless, the goal here is to have twice the power handling and lower distortion in addition to extended bass response. 64 Audio mentions these two drivers use a 9 mm diaphragm composed of a 19 µm thick titanium cone + 25 µm thick PU (polyurathane) surround associated with upgraded neodymium N54 magnets. Additionally, there is a high-precision textile mesh acoustic low-pass filter that was originally developed for the $3700 Fourté Blanc.

The two dynamic drivers cater to the lower frequencies thus and then we have six of 64 Audio's "standard" BA drivers handling the mids and one more for the mid-high frequencies as before from the Nio, although their implementation has been re-engineered to maximize the available space. Then we get to the brand's patented tia driver that is present in the nozzle itself and this happens to be the only in-nozzle BA driver implementation I've been happy with to date. It does so by opening up the balanced armature driver to have an unobstructed diaphragm that helps eliminate unwanted resonances in addition to avoiding sound tubes and/or dampers. With the Volür, things get further improved by the use of a new dedicated tia waveguide which aims to increase the tia driver efficiency and control tuning further. 64 Audio says special diffusion windows were integrated to the front and side of the waveguide which also serves as a mounting mechanism, mating to the mid-driver housing, offering exact driver positioning during manufacturing. These 10 drivers are set in a 4-way passive crossover and, in addition to Apex and Tia, the Volür also features another patented tech called LID (Linear Impedance Design) technology allowing for sources with varying output impedances to not impact the sound signature of these IEMs. I tested this with the U18t before here so you can see how important it is. Overall, the Volür manages to squeeze in all these drivers and audio tech into a small form factor that is also quite easy to drive courtesy a quite low rated impedance of 6.3 Ω (@ 1 Khz) and average sensitivity of 103 dB/mW (@ 1 kHz). You can thus easily listen to the set using a decent dongle, let alone a more powerful portable DAC/amp such as the Questyle M15 I was mostly pairing this with.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm-neutral signature with a slightly elevated bass, smooth treble range, detailed mids, and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear that IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through a capable and transparent DAC/amp such as the Questyle M15 used here. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/12th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the appropriate ear mold fitted to the audio coupler for a separate test to compare how the IEMs fare when installed in a pinna geometry instead of just the audio coupler. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the rated frequency response in the 64 Audio Volür in its out-of-the-box configuration of the m15 Apex modules and the wide bore silicone ear tips. The left channel was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two channels are practically identical across the entire useful 20 Hz to 20 kHz range! This is excellent driver matching, which isn't easy given the increased driver count, and yet what I expect to see from an expensive set of IEMs. I also understand this is a randomly chosen retail unit out of the many being made ready for sale, so it bodes well for the Volür as a whole when it comes to channel imbalance issues, or lack thereof here. Measurements taken after 75 hours of testing, which included these playing a mix of various songs as well as white or pink noise and sine sweeps, showed no difference. There was no perceived burn-in effect thus, and none was measurable, either. The response with the anthropometric pinna in place matched the ideal scenario in the coupler quite well once you realize the latter was done with coupler resonance matching at 8 kHz that in turn shifts the upper mids and treble slightly. Overall, I'd say this is still a valid indicator of how good the seal was when installed in the artificial ear.


Here is the average frequency response for both channels of the 64 Audio Volür plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. This is also why I am showing a second graph using a new target that's based on a more scientific methodology involving a -10 dB tilt (-1 dB/octave) applied to the diffuse field target for the newer, more reliable B&K 5128 but then compensated for my exact 711 coupler instead. If this is a lot of gibberish to you, scroll down to the targets in my database linked above and see the new 5128 section to the left where you can click on the yellow question mark for a brief primer. The bottom line is this target is closer to what many people are likely to prefer out of IEMs and headphones alike. This is especially useful for the higher frequencies and ear gain regions where you will notice the biggest changes from my target. Note also that the second set of measurements are compensated to the target (which is presented as a flat line) allowing you to more easily see how the Volür's tonality deviates from this target. That said, here things are all the more complex because Apex modules are involved. As such, I have four different graphs, which can all be examined separately on a per-channel basis for the Volür's frequency response with the m20, m15, m12, or mX modules installed on the database linked above—it doesn't like umlauts though, so Volür became Volur instead.

Given the standard configuration of the Volür is with the m15 modules installed, let's first briefly discuss how the other three modules change the sound signature relative to what you get with the m15. As evident from the plots above, the degree of isolation is highest with the m20 modules and the least with the mX modules. You can also try to listen to the Volür without any Apex modules installed but that would come off without any meaningful isolation or bass response. The m20 modules increase the sub-bass response over what you get with the m15 modules. It may not feel like much but that extra tilt towards the lower frequencies can help even out overly bright mixes—especially if you are sensitive to the upper treble where there is some spice going on here—while aiding those who love electronic music. I can actually see people going with the M20 module given how the bass is such a standout feature on the Volür but more on that later. The mX modules flip things the other way round and are better suited for music genres without a lot of bass emphasis. These make for a more neutral tonality that helps for music monitoring/mixing where imaging is critical given the clearer mids reproduction. I found it useful for instrument separation with classical music in addition to R&B and jazz as a whole. It also is the closest to both targets but I dare say you end up losing out on what makes the Volür a special set in terms of not presenting bass and the thicker mids here. The newer m12 modules have been my favorite with the U4s and U12t too and this combination is the most balanced of the lot. It presents a sub-bass peak that is now on par with the upper mids in addition to providing a cleaner separation between bass and mids for instruments and vocals alike. In theory this should once again be the winning combo and I went back and forth only to give credit to 64 Audio by saying the default m15 configuration is the best one in my opinion after all.

The overall sound signature of the Volür with the m15 modules can be seen as ranging neutral with a bass boost to even L-shaped depending on how you perceive the higher frequencies. Given how this is clearly taking inspiration from the 64 Audio Nio, I was also glad to have heard it recently at CanJam London. The Nio for me was defined by its bass and thick, warm lower mids. It wasn't the most detailed set and the upper mids needed some work if I had to use it as a daily driver, but there was something about that L-shaped sound which appealed to my warmer sound preferences. The Volür seems to go about mid-way between the Nio and the likes of the U4s in this regard with a bass slope that realistically makes a showing from 350 Hz and under only, despite seeming like it starts from 800 Hz. The end result is you still get bass, and oodles of it at ~11 dB boost with the m15 module, but it's mostly concentrated in the mid-bass and sub-bass with excellent extension all the way down. I didn't notice a muddy or boomy bass here thus, and arguably the bass response is the standout with the Volür. It's by far the best bass of any 64 Audio IEMs I've listened to date including the Tia Trio and the original Fourté in terms of being resolving and also extremely dynamic at the same time. I found myself listening at a lower volume than usual and still being able to discern leading and trailing ends of tones easily. There is good contrast and micro-dynamics at play here, and enough slam and punch to appeal to bassheads too. Bass guitars in particular come off quite visceral and in-your-face, although I did notice kick drums and snares perhaps missing out on the macro-dynamics to an extent.

The lower mids appeal to me personally with the added warmth adding some weight and body to male vocals and many instruments alike. At the same time, this is a more colored tuning compared to Harman-style IEMs that are coming out everywhere and it's not the cleanest or most accurate mids by default. Switch to the M12/MX module and you will see what I mean, especially for percussions and background singers in bands that are not as detailed. Instrument separation is overall quite good as is imaging, but timbre isn't as natural for female vocals and string instruments and the soundstage on the Volür is quite unique. See, vocals present themselves up close and personal—almost as if you are in a jazz club seated at the front row listening to the singer. But then piano keys, violins (most strings), harps, and cymbals have an expansive soundstage akin to a concert chamber. So it can be somewhat jarring when you first listen to the Volür but then it feels like you are standing in the conductor's position in an orchestra, to give you some more context. I suspect this will be a divisive feature of the Volür and I ended up liking it over time for my acoustic jazz and classical music collection but less so for pop and rock—the m12 module, or realistically another set altogether, would be better suited there.

Some of this is because of the upper mids and treble response we get on the Volür. We have the typical 64 Audio early onset ear gain present here too which can result in some female vocals coming off overly forward and others slightly blunted, but overall it still worked fine for me given this particular section was more.. normalized.. than on the 64 Audio previously reviewed sets. The crossover to the lower treble is also quite well executed and things are overall very smooth for piano key fundamentals too. It's what happens with the mid-treble that got me hard. There is a noticeable dip around 9-11 kHz which makes the air in the upper treble all the more pronounced. Indeed, while I appreciate what the tia waveguide is doing here, perhaps it might be doing a bit too much and those sensitive to upper treble resonances may find the Volür discomforting. Cymbals in particular can ring unpleasantly and I ended up adding a couple of EQ filters to help—do this by ear, not based on any graphs. Keep in mind that the graphs above are not the most accurate past 8 kHz anyway and matching the coupler resonance there also exaggerates the mid-treble dip/upper treble peak more than I perceived it in my ears. But you should be aware of this since it can be a potential deal breaker for some while resulting in one of the more unique and detailed presentations for others.


The 64 Audio Volür finds itself priced between the extremely popular 12-BA U12t and the 18-BA U18t/U18s. I have recently heard most of the 64 Audio IEMs although at a trade show without access to my measurement setup so I'll mostly focus on the two shown above for comparisons to the Volür. The U12t is what people think of when 64 Audio comes to mind. It's an extremely comfortable and versatile set that uses a lightly colored tonality which ends up being agreeable to most people who have tried it. The Apex modules also help with bass SPL customization although the actual bass response is not necessarily on par with the competition in 2023. Indeed, I'd say the less expensive U4s outperforms the U12t for bass resolution and dynamics so it's no surprise then that the Volür absolutely spanks it in my opinion. Unlike the U12t where I sometimes had to raise volume to pick up details of snares and guitar strums, I could easily go lower with the Volür for a similar experience that was also better for my long-term hearing. Note also how the Volür has more bass quantity to where the m15 module provides more extension here compared to the m20 on the U12t. The upper mids on the Volür are also a better fit for me and then we see where the U12t's tonality goes a similar route with a mid-treble dip and a spike in the upper treble. This is less prominent than on the Volür however, so the U12t continues to be a safer recommendation for most people. Personally I'd take the Volür if I was spending a similar amount of money, although it must be noted that the U12t can be had for less than MSRP given its age. The same could be said about the U18t which is even older in the tooth now and tuned for a more neutral, monitor-style use case. The Volür is more resolving than both the U12t and U18t most of the way and the U18t does miss out on LID which affects the bass response with some sources, and let's not forget also that you don't currently get the m12 module with the other two sets which is a $99 accessory on its own. The three sets otherwise share the same accessories and build/comfort, albeit the lack of a vent on the other two means you don't have to worry too much about potentially blocking it on the U12t/U18t.

The U4s and Nio are the other two hybrid sets from 64 Audio which do not use the full tia driver system that is reserved for the Duo/Trio/Fourté. If the Volür is too rich for your taste, I'd highly recommend checking out the U4s and my review too since you will get a good taste of what the Volür can do. The Nio is the closest in the lineup to the Volür in going for a more L-shaped tuning that has thick, warm mids. The Volür executes bass and mids better in my opinion, both in terms of tonality and technical performance. It's more resolving than either of these two and on par with the Fourté if you can get over the wonky mids there. I'd still argue the Fourté comes off more detailed from its treble response than purely what the drivers are capable though, and the Volür is a more fun set that also works better with a variety of music genres. It's not the most valid of comparisons but I do dig what the Volür is going for and, despite its higher frequency quirks that I worked around with EQ, I find the Volür to be the best 64 Audio product for my music library and preference.


When you go outside of the 64 Audio lineup, things are of course more competitive with a lot of options in the market. I just happened to have three other sets here recently which are priced very similarly in the form of the Campfire Audio Solaris Stellar Horizon, the MOONDROP Solis 2, and the LETSHUOER Cadenza 12. The new Solaris uses a 1 DD/3 BA hybrid driver configuration, the Solis 2 is a tribrid with 2 DD/2 BA/4 EST drivers, and the Cadenza 12 is the closest to the Volür with its 1 DD/11 BA setup. So interestingly all four in this comparison rely on at least one dynamic driver for the bass response and I'll give 64 Audio the win here again in terms of not only a customizable bass shelf via Apex modules but also the most engaging and punchy bass which is not compromising much on resolution either. In fact, there are very few IEMs out there, including those which cost much more, which do bass better in my opinion! The Cadenza 12 is arguably the best tuned set of the lot in terms of general appeal although note how the lower frequencies are all more similar than not here, which is also why I went with the m12 module response on the Volür to further illustrate this point. The bass glide seems to be a growing trend these days for a warmer sound and I am all for it! It's the upper mids onward where things go all over the place with the Solis 2 going darker than the rest, the Volür being dark and bright simultaneously, the Cadenza 12 closest to neutral, and the Solaris Stellar Horizon going from relatively hollow-sounding vocals to a fairly well tuned treble. The Cadenza 12 would be my winner for those who want one set that does it all, although note that it is a larger set that may not be as comfortable in the ears. The Solis 2 is also large while also being much heavier and is better suited for those wanting a smoother presentation over a more engaging/lively one such as the Volür. The Solaris Stellar Horizon is harder to justify now with these three sets in the market admittedly, so it's likely to be the least recommended of the four.