Some Background:
Aeolus is a new dynamic, open-backed, circumaural headphone from ZMF Headphones, and it is also the realization of a frequent community request. Atticus, the closed sibling of Aeolus, has been a popular high-end flavor-can for the community since it came out about two years ago. In that time, the Atticus has built a cult following for its rich, smooth, and musical tuning, with serious thump. The Atticus was never about neutrality, but about having fun and enjoying music. The Aeolus represents a maturation of that concept, which tempers some of the more exaggerated sonic features of the Atticus, while retaining its character, and bringing a higher level of resolution through its open design.
The Aeolus uses the same TPE driver as the Atticus, so all the differences between the headphones are a result of careful acoustic tuning. By controlling airflow, back-waves, resonance, cup volume, and more, Zach has been able to answer the community’s call for an “open Atticus”. The Aeolus is not meant to be a better Atticus, but instead an offering that gives listeners access to the lush timbre of the Atticus, while trading-off pros and cons where you might often find divides between open and closed headphones. These are namely: isolation, bass extension/quantity, micro-resolution, stage size, image specificity, and evenness of frequency response. The Aeolus is the answer to what an open Atticus would sound like. To find out exactly what that means, you’ll have to stick around.
Bearing all of this in mind, I was very excited to get my hands on the Aeolus for review, and hope to provide useful information for the community, especially given the (soon-ending) pre-order period. I was sent this pair without any requirement that I write a review, and am not being paid here or elsewhere for my reviews.
My Setup:
For this review, I will be running all headphones through my Oppo HA-1, both as a DAC and a headphone amplifier. Music will be run out of my custom-built PC over Spotify Premium via USB to the HA-1. I don’t listen to FLAC for the bulk of my music, and I am most familiar with the tracks to be mentioned, so these 320 kbps versions will be my reference. The highest quality in Spotify was selected, and volume matching was turned off (the settings I always use). Volume across headphone comparisons was matched as much as possible with a BFX digital sound meter sealed to the headphone cups in a cardboard enclosure. All headphone cables used were OFC 4-pin XLR, plugged into the balanced output of the HA-1.
Comparisons:
I will be comparing the Aeolus to the ZMF Auteur, ZMF Vérité, and Sennheiser HD800. For the sake of getting this review out in a timely fashion, I will not be including comparisons to my 007 as I did with the Vérité. I also own an LCD-3F, which is being similarly sidelined. If you’d like comparison notes, let me know what exactly you’d like to know, and I will do my best to answer. I own all of these headphones, and have listened to each of them for a few months at the least (except the Vérité, which is here for review as well).
Test Tracks (Some of Them):
I will be comparing headphones primarily across these, but also other tracks. I don’t make mention of every track in every section where I listened to them, but instead am largely giving my high-level impressions. If you want my thoughts on any particular track or phrase, just ask! I’ve tried to select widely available songs across a spectrum of music that I like and am familiar with.
Track List:
Baralku, by Emancipator, on Baralku
Viices, by Made in Heights, on MADE IN HEIGHTS
Touch, by Daft Punk, on Random Access Memories
House of Cards, by Radiohead, on In Rainbows
Peace Train, by Cat Stevens, on Teaser and the Firecat
Hey You, by Pink Floyd, on The Wall
The Four Seasons, Violin Concerto in G Minor, Op. 8, No. 2, RV 315, Summer III, by Antonio Vivaldi, performed by Adrian Chandler, on The Four Seasons and Concertos for Bassoon and Violin “in tromba marina”
Tamacun - Remastered, by Rodrigo y Gabriela on, Rodrigo y Gabriela (Deluxe)
Warm Foothills, by Alt-J on, This is All Yours
Boomerang, by The Uncluded, on Hokey Fright
Little Sadie, by Crooked Still, on Shaken by a Low Sound
True Affection, by The Blow, on Paper Television
Second 2 None, by Mura Masa and Christine and the Queens, on Mura Masa
Acid, by Ray Barretto, on Acid
ラ・ム・ネ, by Snail’s House, on Ordinary Songs
Build and Comfort:
Given that I have just gone over build in my Vérité review, I won’t go on too long, but let me give an overview of the build of the Aeolus.
The Aeolus is just as well constructed as all of ZMF’s other custom dynamics, that is to say, masterfully. Zach’s designs abound with attention to detail, and high-quality materials. The cups on the unit I have are a pale, unoxidized mahogany, and feature a less ornate grill pattern than that found on the auteur and Vérité, opting for a more sloping and angular pattern. The grill design is a matter of taste, and for my part, I think the grill on the auteur may still be my favorite, partially due to the auteur being my first ZMF open-back. The rod and slider mechanism, as well as double headband are identical to those found on the auteur. The suspension strap and spring steel combination easily adapt, and continue impress with the comfort they provide. Slider adjustment is simple, although it cannot be easily completed while wearing the headphone.
The Aeolus is quite wearable at 445 grams, although about 30 grams can be saved, at a price of $250, on the LTD wood runs of the Aeolus by swapping in the magnesium chassis from the Vérité. The Aeolus will be run in Sapele as the stock wood, and Ziricote for the first LTD run. While on the subject of options, the Vérité pads can be added to any Aeolus order for $60. The unit ships stock with the Universe pads, which I will be using for my review. I will offer brief impressions with the Vérité pads, later on, time permitting.
Listening Impressions:
Bass:
I will only be able to make reference to the Atticus’ bass from a few brief memories, for the sake of those interested to read about it. In general, I am not going to be reviewing the Aeolus as a version of the Atticus, but as its own headphone. With that out of the way, I will say that the bass on the Aeolus is not as elevated in its slamming as that of the Atticus, and that it blends into the midrange more seamlessly. Beyond those broad strokes comparisons, I would really need an Atticus on hand to give insight.
Heard as its own headphone, the bass from the Aeolus is quite satisfying, carrying over some sweetness from the midrange, which we will discuss in a moment. Midbass is more prominent than the sub-bass on the Aeolus, although neither feels out of place. I do enjoy the palpable feeling that powerful sub-bass can impart, and the Aeolus can deliver here. Listening to Massive Attack’s Paradise Circus, and Cane Shuga by Glass Animals, both satisfied in this way, with tactitility to the music that felt cohesive with the overall smoothness that the Aeolus gave to each song. As mentioned, midbass is slightly elevated relative to sub-bass, and is where the TPE driver of the Aeolus shines. Listening to Acid, the bass line came across with excellent substance, and gave a firm foundation to the song, that I sometimes feel isn’t there. The hand drum beats were quick without feeling artificial, and noticing small nuances between each slap was both easy and enjoyable.
Across the frequency spectrum, detail on the Aeolus is reproduced in a very relaxed but competent kind of way. The super scientific analogy that comes to mind is of an expert marksman showing off around a campfire after a few drinks (don’t do this, friends). The shots all hit their mark, but the display is more about having a good time than about absolute focus. What really impresses me is the way in which the Aeolus is, in a very minimally-compromising way, not all about detail, due not to some inherent grain obscuring things, but just because liquidity is emphasized over speed.
Mids:
Oh those creamy mids. Above all other headphones that I have done close listening with, the reproduction of voices on the Aeolus feels the most human. That is not to say that the midrange of the Aeolus has the greatest resolution of any headphone I have heard, but in terms of natural and smooth reproduction of voices, these are an 11/10. Acoustic instruments benefit from this quality as well, but I think because of how much time we spend hearing voices every day, the Aeolus really struck me with regards to them. The midrange response slopes very gently downward as it transitions out of the mid-bass, and carries on with this trend into the lower treble, up until around 5k or so, where the response rises. The combination of this tuning and the lush nature of the Aeolus makes them eminently crankable. It is so easy to listen to the Aeolus really loud. Not because detail feels absent, but because they are just so far from piercing or shrill, and their feeling of musicality didn’t break-up in any of my listening.
Impact in the midrange struck a nice balance, providing a sense of dynamism, without forcing sounds. Edges of notes could stand to be a bit more refined, moreso on trailing edges, but the smoothing that the Aeolus offers did make music easier to get into, and can compensate for some less-than-ideal production value. Spatial placement seems to be less affected by this smoothing, but we will get into these technicalities more broadly in a bit. I appreciate that the sloping of the midrange was tuned to focus on musicality and pleasing naturalness, but does not feel withdrawn or sucked-out. The rise into the lower treble also plays a part in giving back a bit of energy to balance the lush tone of the midrange. The quality, and specifically the enjoyability of the Aeolus’ midrange really is hard to overstate. A capella and tracks with a strong vocal presence satisfy in a visceral way that I don’t often feel when listening to headphones. Drum and acoustic guitar pairings sound damn good in a similar way.
Treble:
The treble of the Aeolus begins by lifting up out of the upper-midrange, and then sloping down again around 10k. There is a bit of dip around 7-8k, but this was only really noticeable on a tone generator. The overall treble presentation continues the trend of smoothness from the rest of the frequency response, although I find this effect to be a bit too pronounced during critical listening. While listening to the Aeolus for fun, or in the background, this more gentle treble presentation is ideal, but when I really want to hear that last bit of bite from violins, or a little edge from the high notes of a sax riff, notes are a bit softer in their attack than I would like. That said, the substance and body of treble notes is still very much there, and impact is solid, if not the pinpoint warhead that I heard a few weeks ago with the Vérité.
To give an example, the chimes and vibraphone (I think that’s what it is) on Viices both sounded clear and full, but lacked some of the sparkle that I have heard from them on other headphones. That said, the same tuning choice/driver property that I believe is causing this presentation is rendering the female singer’s voice enchantingly, and giving me great taut rumble from the bass line. This slightly-damped treble presentation is not distracting or large in its effect, but it does contribute to the overall tone of the Aeolus. There is a small tradeoff being made here, but the Aeolus is doing a good job of convincing me of its presentation.
Technicalities (Imaging, soundstage, detail retrieval, transients, dynamics, separation etc.):
On binaural recordings, the Aeolus can reach wide, and cast a large stage, however, as I’ve found to be the case across the ZMF line, Zach’s headphones won’t make songs sound wide arbitrarily. The Aeolus doesn’t have the quite the three-dimensionality to its staging that you might find on the Vérité or other summit-fi headphones. However, the left-right stage was certainly outside my head, and could reach outside where the headphones end as well. Front to back, the Aeolus also had solid staging, about on par with its vertical presentation, which surprised me. Both the X and Z axes did a better job precisely placing sounds than I expected. To speak more to imaging, specificity on the Aeolus is pretty good, in a way that is consistent with the overall timbre of the headphones. What I mean here is that the Aeolus presents warm, with an emphasis on liquidity. These characteristics can make the edges of sounds harder to locate, and interferes with what can sometimes be mistakenly used as a proxy for detail and precision, i.e. a bright tuning. Despite this, separation is strong enough to satisfy in most cases. I believe that this is due to the Aeolus’ stage pushing out reasonably far, and resolving fairly small increments of space along each axis. All told, it took me a bit of time to understand the actual imaging performance of the Aeolus. In the end, I think only serious detail-heads would trade the natural tone of the Aeolus for that extra 5-10% of imaging specificity. If we could somehow have both, that would be awesome, but we don’t live in that world, at this price, just yet.
In line with, and I believe acoustically related to image placement, is the ability to faithfully and quickly reproduce transient edges. The Aeolus, for similar reasons as those just mentioned, is solid, but not outstanding in transient reproduction. It probably doesn’t help the Aeolus’ case that I am coming off of the Vérité review right now, but the edges of notes on the Aeolus fade in the way that they might in an a modestly damped venue. Trailing edges of notes, especially, linger for just a hair longer, and with a hair less control, than I would like. The first of these factors, the longer decay, is actually pretty great sounding on many acoustic songs, as it does give a more “live” sound. Toward the latter, control of decay is good, but not excellent on my unit. To be fair, wood choice could make a difference here, as might the Vérité pads, both of which are user-selectable to varying degrees. Obviously, I need to review the unit from a familiar baseline, but I’d imagine that there are also systems out there that would help with decay. Leading edges are better controlled, and are part of what give the Aeolus its liquid character, coming into place smoothly, but with impact.
Macro dynamics, are really satisfying and powerful, without feeling bloated or overly thunderous. The Aeolus handles changes in dynamics quite well, especially given its speed relative to other headphones up for comparison today, even across quick passages. Micro dynamics are resolved well, although not at summit-fi (Utopia, 009, Vérité, etc.) levels. Similarly, overall detail retrieval is strong, and detail presentation feels neither forceful nor aggressive. Breaths, rustles, variation between “identical” riffs etc. are reproduced, but you’ll need to listen if you want to really absorb each, and although each detail feels represented, there is undoubtedly more to be pulled out of the mix by a headphone that prioritizes absolute resolution. Overall, the technicalities of the Aeolus are very consistent with the tuning of the headphone, which makes for a coherent experience that is easy to dive into and enjoy for many hours.
Universe Pads vs. Vérité Pads
Not a stock option, but if people are interested, I’ll let you know.
Headphone Comparisons:
Aeolus vs. auteur (auteur pads, mahogany):
As the new middle child in the ZMF open-backed line, the auteur is likely the reference point of most interest in regards to the Aeolus and Vérité releases. If you read my Vérité review, you know that the auteur is the more neutral of those two headphones. It should be unsurprising, then, to hear that between the Aeolus and the auteur, the latter is again the more neutral. I listen to my auteur with the auteur pads, and so with it am listening to what I consider one of the most neutral high-end headphones available today. I have owned my auteur for about a year, and have been excited for a while to compare the open designs for each of these drivers to each other. As a point of reference, my first ZMF purchase came after a few hours of comparing the Atticus to the Eikon, and me going with the latter.
Beginning with the bass, the auteur maintained and reproduced subbass texture better than the did Aeolus. Around the mid/upper bass or lower midrange, the timbre of the Aeolus began to win me over. I heard an about equal amount of slam from both headphones in the bass range, but it was distributed differently, with the auteur having more force lower down. The Aeolus sounded a bit elevated in the midbass compared to the auteur as well, and had a weight to its sound that the auteur lacked. What really differentiated these headphones in terms of their bass, beyond FR differences, is how the bass impact from each of these headphones presented. The auteur hits faster than the Aeolus, and low down, hits more firmly, but also backs off more quickly. In contrast, the Aeolus takes until the midbass to punch hard in terms of peak quality and quantity, and lingers in its force just a bit longer. What this conveys overall is a fast and detailed rumble to the auteur, and a more liquid and dark tone to the Aeolus. I tend to prefer the bass presentation of the auteur, but having owned it for over a year at this point, the mere exposure effect is almost definitely playing a role in dictating my preference.
In the midrange, pretty much throughout, the smooth and lifelike quality of voices and guitars on the Aeolus did huge work on my heartstrings. The timbre of the mids on the Aeolus is, to my ear, more satisfying. With that said, the actual FR of the auteur across the midrange is closer to what I want to hear. The auteur came across as a bit bright, compared to the mids of the Aeolus, both because they are elevated in volume, and because of the auteur is less lush in its tuning. There are some cases too, where the auteur comes across as more lifelike, such as in cymbal reproduction, where the fundamental tang and sparkle cymbals is more energetic and bell-like. Preference across genres here is really hard to decide. In the songs that gel with the Aeolus’ tuning (read: most rock, jazz, vocal, electronic, and hip-hop music), its midrange beats that of the auteur, but for genre-agnostic midrange consistency, the auteur would be my pick.
The treble range is probably what sets these headphones apart the most, in terms of their frequency responses and timbral goals. The auteur really nails what I prefer for treble reproduction: a little controlled shimmer, just shy of venturing into being splashy or glaring. The Aeolus hesitates a bit further from this line than I would prefer, and is a bit slower to resolve edges than the auteur, so its treble feels a bit less lively. That said, the Aeolus never ventures into the land of sibilance, and makes less well recorded music, which can be quite irritating in the treble range, much easier to listen to. As I mentioned in my Vérité review, the Aeolus really saved the day when I wanted to listen to more mainstream hip hop and some electronic music. In orchestral music, however, such as The Four Seasons - Winter in F Minor, violins are given the extra bite they need from the auteur. In some recordings, the more relaxed tone of the Aeolus did capture the grandeur of the orchestra as whole better, but in these cases, the auteur enabled me to pick into the mix that bit more. I’m slightly auteur leaning on the treble, at least for well-recorded music.
Technicalities of these headphones are not worlds apart, but they are worth getting into. Layered effects are, as mentioned, easier to pick apart on the auteur, which also has a bit more refinement in its transients. As a result, however, the auteur loses out on the lushness that the Aeolus gives to many acoustic instruments, which feathers the edges of notes into what you’d be more likely to hear in a live performance. The image is a touch more defined on the auteur, and also a bit more three dimensional. Width of the stage goes just slightly to the Aeolus, although the stage’s edges also feel a bit more diffuse. Dynamic reproduction, in terms of impact, goes slightly to the Aeolus, however the precision that microdynamics, especially, demand are better reproduced by the auteur. Decay on the Aeolus is more live and musical sounding, and notes seem to be more part of the music, rather than their own events.
I have grown used to the auteur, and so, in most cases, prefer it to the Aeolus. With that said, if I haven’t listened to music yet on any given day, and I reach for either headphone, I usually have a larger and more pleasant impression sooner listening with the Aeolus. The naturalness with which it presents music makes me forget that I have heard it another way before, and has me bobbing my head, enjoying. When A/Bing quickly with the auteur, I am reminded just what I value about the latter, but in more casual circumstances, I’m all smiles when the Aeolus is on my head.
Aeolus vs. HD800:
These headphones are way better complements than they are competitors. This comparison honestly feels a little silly. Granted, they are both 300 ohm, open-backed, circumaural, dynamic driver headphones, but the similarities end there. Due to this, and for the sake of getting this review out ASAP, I will not go into as much depth with this comparison. Where the Aeolus is downsloping, mid-bass-to-mids focused, and all about musical liquidity, the HD800 is bass-light, all about technical finesse, and quite lively in the treble region. Comfort on both headphones is great, although for very different reasons. The HD800 focuses on being light and spread out over the ear with thin padding, where the Aeolus is heavier, but amply cushioned, and luxurious feeling.
Let’s begin to unpack how each of these headphones reproduces music. On Viices, for example, the opening taps on the HD800 sound like suggestions, or gentle meanderings, while on the Aeolus there is a substance and weight, albeit small, to each impact. The female lead’s voice is also much more forward and organic on the Aeolus. On Bubble Tea, by dark cat, the Aeolus and HD800 create wildly different experiences. From the former, the song focuses on the female vocalist, and impact from the bassline. Meanwhile, the HD800 plays back a rapid and airy track, with greater detail, but also a fair amount of shrillness from the high-frequency chime notes. Across a range of songs, the peaky treble of the HD800 makes it hard to justify over the Aeolus especially, given its polar opposite, musical reproduction.
In terms of technicalities, the stage on the HD800 is obviously deeper and wider than the Aeolus, although differences in height are less pronounced. Speed also goes to the HD800, but dynamics are really a tossup. The HD800 is faster, so in this sense, its dynamic swings feel quite pronounced, but given the large gap in impact it gives up to the Aeolus, dynamics on the latter feel more...dynamic. More obvious resolution of micro-detail on the HD800 does make dynamics on this scale more noticeable, but the Aeolus resolves at nearly the same level, and with a liquidity that is less fatiguing than the presentation of the HD800 in this area.
There are numerous competitive offerings around this price, but few make so obvious the ways in which the HD800 misses the mark in enjoyability. What the Aeolus sacrifices in absolute resolution, staging, and speed compared to the HD800, they more than make up for in terms of musicality, impact, and vocal realism.
Vérité vs. Aeolus (copied from Vérité review):
The Vérité and Aeolus are certainly not in the same price category, but given that the release of two new ZMF headphones invites comparison, and that I have the Aeolus in for review as well, let’s get into it.
Build is not really a category that deserves much time. The Vérité is a bit lighter due to the Mg chassis. Both headphones are finished beautifully, and built durably. I will go into a description of the Aeolus’ build in its review, coming Soon™.
To get right to sound, the Aeolus is just a freaking fun headphone, with a nice jump in technicalities and evenness as compared to the Atticus, that makes it so easy to listen to. More than any headphone in this review, including the Vérité, I found myself bobbing my head, or up and dancing, listening to the Aeolus. It’s not as technically proficient as the Vérité, it’s not as fast, controlled, holographic, or detailed, but it is a massive contender in the ~$1,000 headphone market. The mids on the Aeolus maintain a lush and inviting character that Atticus owners will know well, with guitars and vocals coming through especially in an exceedingly natural way. However, the mids are now transitioned into from a less booming, but still punchy, bass range, and are followed by treble that I think needs just a bit more bite on some classical tracks, but which makes a lot more recordings sound good. I still need to see how the Vérité pads alter the response of the Aeolus, and have a hopeful guess that they will bring the treble to an awesome spot.
Compared to the Vérité, all of this results in a headphone that is more friendly and forgiving, but less wowing and engrossing. The Vérité can resolve to an extreme, but would not be my go-to choice for “low-fi beats to study to” (I hope for obvious reasons). Beyond the fact that I would feel a bit guilty ignoring the Vérité, it is good at being the microscope with musicality that the HD800 never was, and the headphone with slam and speed that doesn’t drill detail into your ears with its metallic tuning. The Vérité isn’t a headphone that’s easy to put on the back burner mentally, despite its somewhat down-sloping tuning. Meanwhile, the Aeolus presents a great value for the enthusiast who wants a take on the ZMF sound that is less about absolute technical proficiency, and more about fun. That said, the Aeolus does take a big step toward traditional audiophile characteristics compared to the Atticus, and I think many people will love it for that reason.
Closing Thoughts:
More than any other headphone I have on hand, the Aeolus makes me forget about my system and just jam out. More often than we’d probably all like to admit, that’s all we want out of a headphone, a good time with the music. To be fair, there is absolutely still space and pleasure to be found in absolute resolution and speed, and there are headphones which cater to that desire. That said, the warm tuning and lush presentation of the Aeolus presents a more refined and audiophile-friendly version of what the Atticus made available a few years ago: a high-end intersection of pleasure and resolution. Neither sibling-headphone obviates the other, and the Aeolus is a very attractive offering in the ZMF line, as well as in the ~$1,000 headphone world overall. For the listener who wants to enjoy first and go detail-hunting second, the Aeolus is a great choice. Overall, the rich and impactful sound, coupled with the strong-enough resolution of the Aeolus makes it easy to recommend to those searching for a new headphone to enjoy, in the $1,000 price range.
Thank you to Zach and ZMF for creating the Aeolus, and sending them over for me to check out. I have enjoyed my time with the Aeolus a great deal, and appreciate the opportunity to review them.
Specs:
Frequency Response: Approximately 10 Hz to 25 KHZ
Impedance: 300 Ohms
Sensitivity: 99 dB/mW
Warranty: Lifetime for Driver, 3 years parts and mechanical
Weight (est.): 445g
Pads: Universe (Vérité pads optional +$60)
Case: Seahorse SE 430
Price: $999 pre-order, $1199 list price
Aeolus > Atticus > Auteur > Verite > Eikon.