Contrarian Twins: MrSpeakers AEON Flow Open & Closed Planar Headphones - Review & Comparison

February 16, 2019

I’ve read a lot about MrSpeakers since their introduction, but for a broad conspiracy of reasons had never gotten to spend any useful time listening to their headphones. In fact any such exposure had been limited to a smattering of encounters at local meets - which are not necessarily ideal conditions for any kind of real assessment. So it was with some anticipation that I opened the unsurprisingly-identical-except-for-a-sticker, boxes for the subjects of this review/comparison.

The AEON Flow Closed and Open models are, a planar-dynamic designs, and are among the newer models from Dan Clark, currently sitting in the middle of the MrSpeakers overall line-up. The brand began life with Dan’s well-regarded modifications to other headphones and he has, over time, moved his business over to offering models that are all his own design - right down to the drivers.

Thanks to “The HEADPHONE Community” and their “Community Preview Program”, I have had both the AEON Flow Open and Closed on loan for about a month in order to review and compare them - and they have now been returned.

Technology

Both AEON models feature two, proprietary, technologies that were first developed by Dan for his flagship “ETHER” line of headphones and both of which are covered in detail, complete with illustrations/animations, on the MrSpeaker’s “Technology” page.

The first is “TrueFlow” which aims to reduce detail-masking turbulence as air flows around the driver’s motor assembly, by using specially shaped ports in the magnet structure to channel and smooth the air-flow. This is conceptually similar to the “Fazor” technology used by Audeze, although the implementation is entirely different.

The second is called “V-Planar” technology, which aims to make the movement of the driver’s diaphragm more linear and pistonic than is possible with standard, flat, planar diaphragms. This is purported to allow greater movement of air at low frequencies and reduce distortion across the board.

Review Equipment & Material

Sources and amps used in this review includes the Chord DAVE, Chord Hugo 2, Sony NW-WM1Z, Questyle QP2R, Woo Audio WA234 Mk2 MONO and SPL Phonitor x.

Headphones used, for comparison, include the Focal Elegia and Clear , Massdrop x Focal Elex and Fostex TH900 Mk2.

The majority of the music I use in my evaluations is in “Red Book” CD format (16 bit, 44.1 kHz), most of which comes from CD rips; an initial playlist for my audition listening can be found here. Where appropriate/referenced I utilize a number of high-quality, high-resolution, albums, needle-drops, and also some native DSD content.

Build

Materials, fit, finish, presentation and the general sense of solidity the AEON Flow models are excellent. They have a unique, rich and high-end look, with their irregular ovoid ear-cup shape which is further enhanced by the rather hard to photograph dark metallic blue/black shells. The colors shift slightly as you turn them in the light, and the finish has a depth to it that is more common to high-end automobiles than it is on mid-level headphones. The carbon fiber inserts on the closed-back model add even more in this regard. Overall I think they’re among the most distinctive and attractive headphones I’ve come across and they exude the feel of a premium product.

Cables are a dual-entry affair and are finished with Hi-Rose-style locking, polarized, connectors. They have a very solid engagement into very secure sockets in each ear-cup, and will not accidentally pull free, fall out, nor slowly give-way to intermittent contacts. The cable is sheathed with a soft, pliant, non-microphonic weave and is very flexible.

For those that want to make their own cables, you can buy the necessary connectors, and find the pin-outs, directly on the MrSpeaker’s site.

Accessories

Both versions of the AEON Flow ship in the same package, with the only things differing being the headphones themselves and the product sticker on the outer case.

You get the headphones themselves, which are nicely cradled in a purpose-made and form-fitting case, your choice of “DUMMER” (Distinctly Un-Magical) cable terminated with either single-ended 1/8” (3.5mm) TRS with a screw-on 1/4” (6.35mm) TRS adapter, or a 4-pin XLR balanced cable, and a tuning kit that includes three pairs of tuning pads (one pair of which is pre-installed) which can be inserted to subtly alter the balance of the sound (more about which later).

The case is technically semi-hard-sided, similar to the Focal cases, in that it is quite sturdy and will do a good job of protecting your headphones in almost all circumstances, short of dropping something very heavy on them - but isn’t a truly hard-sided design like the near-indestructible Pelican or Seahorse cases - it’s also usefully smaller, lighter and easier to live with. It has room inside for a couple of pairs of cables and the tuning pads, in the lid behind/inside a little mesh compartment.

Comfort

I found both models of AEON to be among the most comfortable headphones I’ve had on my head and they are extremely easy to wear for long periods of time. At 330gr (for the closed back), they are a couple of ounces lighter than, say, the HiFi-Man Ananda, which are perhaps the closest obvious competitor, and yet the AEONs manage to feel far more substantially built at the same time.

The soft, smooth, pads have plenty of depth and seal easily without fuss. They’re deep and plush enough that they should present no issue for those wearing glasses. Despite their more compact shape, they left plenty of room for my not-very-dainty ears without them contact the insides of the pads or the drivers. Even with the closed-back models I didn’t find any notable build-up of heat, and clamping pressure is just-right - being lighter than things like the Sennheiser HD6XX series or the Focal Elegia, but not so light they don’t say put.

The suspension-style headband is sturdy, with friction-held adjustments that are easy to adjust and then stay put without drama. The metal single-point yokes are sturdy and firm and while they might not look as solid as the more common dual-sided attachment, they’re more than up to the job here with the ear-cups remaining appropriately oriented at all times.

Sound

My expectations coming into this were, primarily, set by what I’d read about the “higher-end” ETHER line - which suggested that MrSpeaker’s “house sound” was leaner or brighter than my normal, more neutral, references (and preferences). Right out of the gate it was apparent that neither the AFC nor the AFO were, in anyway, lean-sounding nor thin/bright. Indeed, with the AFO in particular my immediate reaction was they were well on what for me is the wrong-side of “warm”, and the bottom end was rather overzealous. I had to stop and check to see if I had put the AFC on first, by mistake, as I’m far more used to that sort of bass-emphasis from closed-back cans.

But, no … it was the AFO I was listening to …

It is from both that initial experience, along with my continued listening, that yielded the title prefix for this review: “Contrarian Twins”. By which I mean that as close as they are to each other in terms of build and technology, which is more than enough to consider them to be virtual twins, their respective characters are, for me, the polar opposite of what one might expect.

Switching back and forth between the open and closed models showed that I was, indeed, getting more bass presence from the AFO than the AFC and I think that is down to the AFC being better damped/controlled at lower frequencies than the AFO. And it didn’t take much more swapping between the two to form one opinion that has remained consistent for me during my entire time with these cans … and that is that I like the AFC rather more than I do the AFO.

The above, un-compensated (miniDSP EARS “raw” - microphone compensation only, calibrated at 300 Hz), frequency response plots for the AEON Flow Open and Closed, both with the default filters in place (the white “2-notch” filters are pre-installed at the factory), also show this inversion of expected character quite readily.

Power

Before getting into more specifics, it is worth pointing out that both of these cans respond well to power. Their unusually low impedance of 14 ohms means that, at a superficial level, they might be perceived as being “easy to drive”. That’s only half the story though … as while they don’t need much voltage swing, they do require correspondingly more current. In fact, they require rather more power than I would have expected to sound their best, and without it I found them to sound congested, flat and somewhat wooly in the bass.

While you certainly don’t need a monster amp to drive these (there are desktop options at $100 that are ample, power-wise), I felt they were unsatisfying out of most phones and dongles I tried and really deserve a source with a decent amp stage (most standalone DAPs and modest desktop amps are fine). The QP2R, in high-bias, high-gain, balanced output, ran into a wall with these with content that has lots of low-frequency energy - resulting in an unsettled bottom-end and some definite clipping and distortion.

Additionally amplifiers with (relatively) high output impedance (e.g. the headphone output on a Topping DX7s) may not be suitable here. While planar-dynamic designs usually exhibit largely flat impedance vs. frequency curves, high-output impedance amps may run into other issues (distortion, stability) driving such low-impedance loads.

Tonality & Timbre

The AFC are generally pretty neutral in tone, where the AFO are, as already mentioned, notably warmer with emphasized lower registers. For real instruments and especially orchestral pieces, I find this tilts things in favor of the AFC as the presence of tones in the lower registers is exaggerated too much and upsets the balanced of the piece for me with the open back model; the AFO are more successful with electronic pieces, but the AFC still sound more natural.

I moved away from using mid-range planar headphones due to often finding them imparting a sense of artificialness or plasticity to the timbre of natural instruments - fortunately the AFC and AFO do not fall foul of that problem. Cellos sound like cellos, violins won’t be confused with viola. Timpani don’t sound quite right out of the AFO, but that is more about impact and presence than actual timbre. Brass instruments bite nicely, if perhaps a little harder with the AFO. Cymbals exhibit a tendency towards steeliness on the AFO that I don’t hear via the AFC.

Bass

Deliberate or not, the AFO is definitely the bass-emphasized version of these cans. While the level of raw bass elevation is not high, its contribution to the overall sound seems significantly exaggerated by a wide dip in response from the low-mid range up through the lower treble, and the end result is that the AFO is obviously heavier down low and has some bleed into the mids. Another factor here is that the bass delivery with the AFO seems less precise than with the AFC, so while there’s more of it - it is less tuneful, and feels less controlled, and somehow “slower”, than in the closed-version. That’s not to say I found the bass on the open models to be slow in absolute terms, just not as quick and deft as with the closed-back model. Overall bass delivery is pretty linear, as is typical of planar designs, and is capable of entirely satisfying rumble and growl.

The AFC fairs rather better when it comes to articulation and delineation, making subtle details and tunes in the baseline easier to discern and follow. The have a slightly faster sound, and more impact/speed to my ears than the open-back version, and exhibit a more deft and precise delivery.

There is no lack of bass presence with the AFC, but I would take them and EQ up the bass a tad if I wanted more, rather than going with the AFO and trying to EQ the bass levels down.

Midrange

Excepting some slightly muddying-bleed into the lower-mids with the AFO (that’s not there with the AFC), the midrange is clean, smooth, nicely resolving and even. I heard no artificial sweetening of the midrange, and while the AFO is somewhat recessed here (or that’s how it seems due to the bass levels), vocals are appropriately present and have a natural presentation.

The actual quality of the midrange is, excepting some bass-bleed on the AFO, identical between the two models. But if you’re a mid-centric listener, then the AFC steal the show here simply by virtue of it being appropriately present in the overall delivery and it not being overwhelmed from below.

Treble

Extension is good, notes sparkle appropriately, it’s easy to hear the strike on a cymbal decay away, and there is little in the way of apparent grain unless things are pushed quite hard. Air, and the sense of space, in a recording seem, rather paradoxically, more restricted or subdued with the open-back model. It’s present in both models, but the closed-back version of these headphones sound, well, more open than the open-backed ones.

Female vocals, from my “torture track” selection, exhibited no sibilance and remained well controlled. There were no wince-inducing moments, even at higher volume levels. Tension, where present in the performance, was clearly audible from both cans, but remained controlled and representative of what they were being fed.

Dynamics & Transient Response

Raw transient response here just favors the AFO in technical terms, but the leading edges of notes sound cleaner with the AFC and that results in my perception of them being somewhat more resolving and “faster” than their open-back brothers. The often mentioned “planar” speed is generally in evidence here, and very complex, staccato, pieces are tracked well with the near instantaneous stop/start

Dynamics, in the macro sense, are very solid. There’s good slam and impact, with an excellent sense of scale and power to larger productions. Anything you play through either model sits on a very solid foundation. Micro-dynamics, tiny fluctuations in level, as you hear in low vocal tones as gravel or grain, or subtle emotional cues in the wavering of volume or note are a little less successfully portrayed. I find good, traditional, dynamic headphones usually do a better job than planar models here, and that’s the case with both the AFO and AFC, with the HD650 or the Focal Elegia both exhibiting better micro-dynamic resolution - clearly audible in subtle changes in bowing pressure in violin solos, or in deeply textured,vocals.

Detail, Resolution, Layering & Separation

The AEON Flow twins both exhibit very good resolution of detail without any artificial sense of exaggeration. Both models allow you to hear well into the recording and tease out individual elements of it - in a manner that makes them easy to follow. While typically I find that planar drivers lose out to better dynamic drivers here, I did not have that impression with either of the AEONs. Notes are distinct, as are instruments, but still present in a fully coherent manner.

Stage

Raw placement and projection of what is where, especially any sense of 3-dimensionality or depth is much harder to hear with headphones and I found both the AFO and the AFC to render a flat-but-curved that sits just in front of the eyes. Lateral delineation is very good, and the stage exists beyond the apparent width of my head, and it is easy to place individual voices, instruments, or notes from left-to-right.

The sense of space/size to a venue is another factor that comes in here, and in this case the AFO did a more convincing job of making me feel like I was, for example, actually sitting in the Trinity while listening to Cowboy Junkies’ “Mining for Gold”.

Filters/Inserts

Over the years, MrSpeakers have offered various user-installable/swappable “inserts” or “filters” for subtly tuning the sounds of their headphones (I believe they were called “Doggie Treats” for the “AlphaDog” line of cans). The AEON series is no exception. Three such filters are included, a very open “Black” filter, and two white filters of different density which are differentiated by having one or two notches in their edges - you can, of course, use them without any filters installed too and you could, if you wished, combine them - though based on listening I wouldn’t.

Using the filters is simple; they just lay against the driver cover inside the headphone and are extremely easy to install and remove (no tools, takes seconds, is non-destructive and they stay in place without issue).

In both cases the basic nature of the changes is similar for the same filter type for both headphones, even though the specific effects do vary somewhat.

Both of these plots are zoomed on the amplitude axis to make it easier to see the differences each filter yields - so don’t compare them directly to the other plots in this review. Calibration was done once for each headphone using the black insert, and not changed or reset for the other filters so that you can see the effects on relative level as well. Microphone compensation only, no headphone curve applied. The peak around 4-5 kHz is a consistent artifact of the miniDSP EARS

For my personal tastes I found I liked the AEON Flow Closed with the default 2-notch white filter installed the best. With the Open model, while using no filter helped in terms of bringing up the non-bass components of the signature to a more even point, and helped with the bass-bleed into the mids, the top-end then got to be a bit too much. Ultimately, the black filter is where I settled here, which was a definite trade-off … it helped with the bass transition at the cost of still a bit too much tension in the top-end.

Isolation (AEON Flow Closed)

In general, my primary use for closed-back headphones is when I either need to minimize external noise or where I need to contain the sound so as not to disturb others around me. Outside those scenarios, the vast majority of my listening is via open-back headphones or speakers. As such, the isolation offered by a closed-back headphone is one of its most important factors for me.

The graph, above, shows how the AEON Flow Closed fair in this regard, directly and in comparison to the next-most-recent closed-back headphone I reviewed - Focal’s Elegia. As you can see, the AEON lets much less sound leak out than the Focal model. I didn’t find any issue with using the Elegia in public/next to my partner at night at normal levels, but with the MrSpeaker’s model you can really crank these up and you will not be bothering anyone around you. And, outside using active noise-cancelling, these shut out the outside world as well, or better, than any other headphone I own.

The environmental background noise level was at 40 dB (typical of a quiet library) for this process and tests were made 1 meter from the ear-cup. The vertical axis indicates how loud the headphones had to be playing for a given frequency to be audible to an outside listener. Thus it shows that lower frequencies are generally less audible - requiring a level of 120 dB for a 100 Hz signal to be externally audible, and dropping to 85 db for 1 kHz and 10 kHz signals to be perceptible on the outside.

Comparisons

Since I’m already comparing two headphones directly, this will be a bit different to how I’ve done comparisons in other reviews. Here I’m just going to show the relative frequency plots of what I think are the headphones I own that are most likely to be cross-shopped with the two AEON Flow models.

You’re welcome to ask in the accompanying “HEADPHONE Community” forum thread if you want more specifics (don’t do it in the comment section following this review, I rarely read them). The linked forum/discussion threads (see the end of the summary) are the place for follow-up discussion.

AEON Flow Open vs. Open Backs

The closest open-back models I own and had on hand to measure against are the Focal Elex, Elear and Clear. Note that the graph here has its amplitude axis zoomed in to make it easier to see the differences between each headphone.

AEON Flow Closed vs. Closed Backs

The closed-back models represented are either direct price-competitors for the AEON Flow Closed, or can be found used for similar prices (and the more expensive models are there more for comparison than because they’re necessarily in the same price/value bracket).

Note that all measurements are microphone-calibration only (no headphone compensation), were done at 84 dB @ 300 Hz on a miniDSP EARs unit. The plots for the different filters on the AEON models were set at 84 dB with the 2-notch white filter, and the levels not changed when switching filters.

Summary

Beyond the contrarian natures of the AEON Flow Closed and Open, I am left with a strong preference for the closed model. Normally I prefer open-back headphones, but in this comparison that is decidedly not the case. I cannot think of any scenario in which I would opt for the AFO here. The AFC is the same price, sounds better, looks better, is otherwise identical in terms of build (excellent), comfort (superb) and package AND offers significant isolation.

Put another way …

I like the AEON Flow Closed a lot. It’s a great sounding little can and offers very solid value.

But I would not personally buy the AEON Flow Open. It seems superfluous given that the Closed version does almost everything, and certainly everything I care about in a headphone, better and with no apparent upside.

While I can see a bass-head preferring the AFO model, bringing up the bass of the AFC to a similar level via EQ still results in an overall superior result (for those times when you want more than neutral bass) than using the AFO and trying to tame it’s bass via EQ. And if I was really after a bass-head can, I’d be looking elsewhere entirely anyway.

I suspect my response to the AEON Flow Open would likely have been more positive had I not reviewed it side-by-side with the AEON Flow Closed - I just think the closed model is a better headphone, with the added benefit of isolation and with no (for me) practical downside.

Even without the existence of the AEON Flow Closed, the AFO is still not a headphone I’d choose for my own use. The bass is too present and not well enough controlled - bleeding into the mids … and if going against other open-backed headphones, around the same price, I vastly prefer the overall delivery, superior dynamic punch and raw resolution of the less-expensive, if not quite as pretty, Focal Massdrop x Elex.

In comparing to the closest closed-back headphone I own, the Focal Elegia, I would put them on a fundamentally similar level to the AFC - different, certainly, but overall equal - you’re just trading off different strengths. My personal preference is for the superlative dynamic performance and resolution of the Focal design, but if you want a bit more weight to the delivery and/or you want more isolation, then the AEON Flow Closed are probably a better bet for you.

Anyone considering a closed-back headphone in the same range as the AEON Flow Closed should make sure to give them a listen. And if you’re looking for an open-backed planar headphone at this level, and you include the AEON Open in your list then I’d be inclined to include the AEON Flow Closed there too, even though it is closed, as it’s not what I’d expect from closed-back headphones.

They really are contrarian twins.

Written by Ian Dunmore (@Torq)

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Join the discussions about the MrSpeakers AEON Flow Closed and AEON Flow Open at "The HEADPHONE Community".