Dan Clark Audio AEON Flow RT Closed

I’m here today with a review of the Aeon Closed RT, purchased back in 2021 for $500 as my first experience with DCA headphones. I eventually used it for a 15% Club DCA discount on the $4k Expanse and $900 Noire, so I’ve certainly gotten my money’s worth from the Closed RT.

No photos this time since I sold these to a friend before taking them.

Build and Accessories​

For the price, the Aeon Closed RT is definitely one of the best built headphones out there – while it’s not especially premium (being mostly plastic-adjacent build), everything is solid, well fitted, and free of any odd creaks or squeaks. The Hirose connectors are my favorites, being secure, extremely durable, and easy to use. They do make replacement cables more expensive, but many custom cable shops seem to carry them now.

On the accessory front, the Aeon RT comes with a carrying case, cable, warranty card, 4 tuning filters, and the pre-attached ear pads. Nothing incredible, but good for the price. The carrying case is a nice and large hard shell, since the RT doesn’t fold like DCA’s higher end headphones, but this extra space makes for a nice area to store the cable and some other odds and ends. It’s certainly very protective, and a nice little value add.

The stock cable isn’t the best, and worth replacing fairly quickly. It’s heavy and a little stiff, but worst of all is that it’s very microphonic. With the price of Hirose connectors, a replacement cable hurts the value proposition of the Aeon RT quite a bit but is a necessary expense in my opinion.

Finally, the headphones come with 4 pairs of tuning pads, ranging in how much dampening they do. The thinnest black foam might as well not exist for how little it changes the sound. I’d say that at least it protects the drivers from dust and debris, but there’s already a thin fabric filter. Can’t hurt, I guess. On the other end, the white pad with 2 notches will significantly reduce the treble and effectively bring up the mids and bass.

It's nice that DCA provides these as options, effectively giving 5 different tuning options (even if the black foams aren’t much different from not using any filters). For this review, I used mostly the two white pads (1 notch and 2 notches) as well as no filter.

Comfort​

Just as important is comfort, where the Aeon Closed RT really shines. The earpads are large enough for even my Dumbo ears, although the tips of my ears do touch the drivers and edges of the pads. This personally didn‘t bother me, and there were no sharp edges, but this is obviously very subjective.

They extend quite far – you’d have to have a pretty large head before that becomes a concern here. The earcup pressure is snug, but not skull crushing. One small complaint here is that they can be slightly uncomfortable if you wear glasses, depending on the width and placement of the legs.

Bass​

The bass on the Closed RT is best described as ‘lean’ in kind terms, or ‘anemic’ in less kind terms. There’s really no way around the fact that, without any of the filters, the Closed RT has a frequency response shaped like / a slash. While there is bass, you’d have to turn up the volume to get much sensation of rumble, thump, or impact. And at that point the treble becomes piercing and fatiguing. And while the bass takes to EQ well, you’d need a pretty significant bump to bring the bass and subbass up to a ‘normal’ level. While things like iFi’s XBass II will bring up the low end, it ends up being very V-shaped instead of normal sounding.

Mids​

Mid recessed, hollow and thin due to little bass. This applies to all kinds of vocal, both female and male, high and low. Lower voices tend to lack real rumble and it often ends up coming across as grit instead. With thicker pads, the mids become natural and filled out, but this comes with sacrifices to the treble and treble detail (not necessarily badly).

Treble​

There’s an icy edge to higher vocals – the imbalance between mids and treble is so severe that it sounds like the higher portion of a voice within a single sound is over-emphasized while the lower portion is recessed. Miwa doesn’t sound hoarse, but instead oddly thin and piercing at times with a slight grain to her voice. Inhales and other breath sounds are almost sharp at times, as if they singer was gasping for breath. There’s also slight sibilance on s sounds and cymbal hits.

Adding the thickest (white with two notches) filter brings down the piercing sensation and makes voices more cohesive, but the treble is still fatiguing and slightly grainy. The filter also brings down the attack on leading edges, leading to a more smoothed over and generally less detailed sound. This isn’t necessarily a bad thing – the sound becomes much easier to listen to and goes nicely with the comfort and isolation to make for an all-day pair of headphones.

Conclusion​

Overall, you can definitely tell that the Aeon Closed RT is the cheap little sibling of the bunch. It’s got the weirdest tuning, weakest detail retrieval, and least compact build. However, this doesn’t mean that the Aeon Closed RT is a bad headphone, especially for a closed back at this price.

I don't always “need” a closed headphone. For my own preference, I've historically chosen open backed headphones for their more natural tonality and openness of the sound staging. But times they are a changing. I find myself working from home more often than ever before. And with two kids still in the nest and three rowdy dogs, a good closed back set seemed to be in order.

Because I typically grind my teeth at the sound of ANC headphones, I knew that I'd want a set with good passive isolation. And because of a degenerative issue in my neck, I'd also need a headphone that was lightweight and comfortable to wear for long periods. Lastly, I didn't have a big budget. This should be easy enough, right?

I first thought about the Audioquest Nightowl Carbon. They did fit much of the criteria that I was looking for. The issues with the NHC were the somewhat wonkey frequency response that required a fair bit of EQ to get to my liking and also they were out of production and not easy to find on the used market. Then I remembered seeing the sale pricing for the newly retuned (RT) version of the Aeon Flow from Dan Clark Audio. I needed to take a closer look at them. They were lightweight at 327 grams...check. The new tuning put them very close to the Harmon curve which I find natural sounding and enjoyable...check. And the price was coming in at a sweet $499! I knew that I needed to give these a shot.

I guess the Aeon Flow RT must be quite in demand as it took about two weeks to get them in hand after placing the order. When they arrived everything looked great except they came with a singled ended cable instead of the balanced cable that I ordered. I contacted support and Sue reached out quickly and had a balanced cable on the way with a return label provided to send back the SE cable. This is how customer service should be handled!

I did a break in period of about 125 hours to get those planar pleats moving freely. So after the fifth day, I finally started to put them through the paces with my usual test tracks. Here is my test track playlist:


*Nathaniel Rateliff: In Memory of Loss (Brakeman and Oil and Lavender)

*The Civil Wars: Barton Hollow (I've Got This Friend)

*k.d. Lang: Hymns of the 49th Parallel (Hallelujah)

*Ry Cooder: Delta Time (Shelter from the Storm)

*Carmen Gomes: Carmen Gomes Sing the Blues (A Fool For You)

*Doug MacLeod: There's a Time (Black Nights)

*Rodrigo y Gabriella: self titled (Diablo Rojo)

My test track list sometimes changes depending on my mood and preference. But the songs I use always cover some common ground. They offer examples of:

*Good staging. Not just width and depth, but depth cues and instrument placement

*Textured bass response where instruments can be clearly identified and enjoyed

*Well recorded male and female vocals for mid range evaluation especially natural tone

*Ability of the treble to extend without harshness and fatigue

And lastly, how much did I enjoy listening to the test tracks? Was the experience monotonous and boring. Or did I get drawn in and continue to listen to track after track, excited to hear subtle detail and nuance that I may have missed before from these tracks that I've listened to dozens of times.

So let's get right to it. How does the AFRT sound and did I make a good choice?

My pair of AFRT came with the white single notch filers installed for each cup. After experimenting with all the included tuning pads, the original turned out to be the one that I preferred the most. The white tuning pad gave me the best balance of tone, warmth and detail out of all the tuning pads included. All impressions offered here will be with the white one notch pads installed.

Two things jumped out at me quickly when going through my test tracks. First, was the bass response. While it's slightly elevated, it's clean nicely textured and man does it hit hard. The bass here was taking me back to the old days of the OG he400 with that visceral punch that puts a big smile on your face. Bass response just seems to dig effortlessly all the way down to about 30 hrz. I have to admit that while my taste have gravitated towards a more neutral signature, I'm still a bit of a closet basshead provided that we are talking audiophile quality bass.

The second thing that strikes me with AFRT, is that while the bass might be the star of the show these headphones are quite even across the spectrum with juicy detailed mids and airy highs. Of course any headphone that I review are based with the knowledge of the sticker price in mind. That being said, I would evaluate and judge a $2000 pair of headphones differently than a $500 set. So now let's consider that the AFRT has a sticker price of $500. How would I evaluate them at that sticker price? I would easily put this headphone in a “best in class” category for it's price/performance ratio. This headphone is simply a whole lot of fun to listen to music with and it comes with a good sprinkling of audiophile pedigree from it's older siblings.

Anyone looking for a very good pair of headphones with a $500 budget should have the AFRT on their shortlist.

I’ve listened to the original Aeon flows in the past and while I had preferred the open back version I really liked the concept of a lightweight closed planar for office use or at home when I don’t want everyone hearing what I’m listening to. The only gripe I had with the closed OG aeons is I felt they sounded too cold and lean on the low end. When I saw that the Aeon flow series was being updated with new internal tuning I was stoked about the closed version again. After purchasing and receiving them I can definitely say I really dig this “re-tuned” edition of the closed aeons.

Onto the review of the sound! My personal preference are a dynamic hybrid iem where I get good hitting bass and have a brighter treble with decent mids. When it comes to an over ear headphone I prefer a spacious sound with a deep low end, the mids to be more further away from my ears and the highs to be a little bright with some sparkle. I listen to a lot of genres but I hover in the classic rock, blues and edm music with some rap here and there.

Gear used
iPhone X with headphone adapter, FiiO m11, smsl sh8/su8 combo and Schiit heresy.

*note*
I did my final listen and writing of this review with the black foams installed. I initially liked the black felt tuning pads with the stock cable. However after converting two null audio cables to the hirose connectors the sound changed enough that I enjoyed the black foams the most. All sound impressions will be off the black foam tuning pads. The cable used was the null audio lune mk.6 cable in 4.4 pentaconn I converted to use with the DC Audio hirose connectors. I will have some notes of the stock cable later in the review.

Lows- Lows have a nice and clean “quality planar bass”. Fast and accurate. Tuning pads will affect this decently. With my setup I really like the low end and I still get a decent thump and rumble which I can appreciate.

Mids- Via my setup, the mids end up sounding a little further away from the listener and feels separated from the rest of the instruments. Vocals sound good-great at times.

Highs- The tuning pads IMO affect the highs the most. With my setup I get a really clean treble with nice and clear sound and some nice sparkle. Hi hats and cymbals sound great and as I was a big drummer from the age of 5 till I moved into an apartment as a grown up I really like to have great sounding drums. That being said these do detail retrieval and micro details decently. These won’t be fighting with the heavy hitters but it does really really well for the price.

Imaging- Imaging is really good! Everything feels super accurate and I don’t notice anything strange in this department.

Soundstage- A nice wide sound. Not nearly as wide as a good set of open backs but this reminds me a lot of the Sony mdr-z7 which was a semi closed with a wide soundstage. When using no tuning pad or the black foams there is a light echo you hear which adds to the feeling of a wide soundstage and I really enjoy it.

Stock cable- So with the stock cable you get a lot of microphonics which can get irritating fast. The sound is what I consider perfectly fine for the aeons as you can adjust the flavor of the sound with the tuning pads slightly. If you don’t move around much I find the cable to be decent. With the stock cable I found the black felt gave me a good soundstage at a small drop to the low end but had a nice sparkle top end. The white single notch muffled the highs and soundstage a tad too much for my taste.

Cable rolling- I converted an old null audio lune mk.4 in 2.5mm and a lune mk6 in 4.4mm pentaconn. The two sound fairly similar which makes sense as they usually only do cosmetic changes between new lune cables. The mk.6 is my current daily driver/cable since I have the most adapters to use with 4.4mm. The cable does actually change the sound enough to notice the second you play music after switching from the stock cable. My other planars could care less about cable swaps but those are all open backs so that might be the reason why. This change includes a slightly wider soundstage but the most noticeable was the slightly warmer sound. It was enough that I was able to swap from the black felt to the black foam tuning pads and get darn close to my preferred over ear headphone sound. The low end isn’t bass head worthy but it still gives a nice rumble and echo and the mids move a little further out and the highs end up rather clear with just enough sparkle to make me smile quite a bit. If you can’t tell, I really like this combo for the Aeon flows.

Amping- So this is where things got fun for me. I love when things need to be amped cause that means the gear I have is actually worth it. Out of my iPhone these don’t get loud at all, they get to a “I can listen to this in bed as I get ready to fall asleep cause it’s pretty quiet” but that’s it. It also sounds a little flat and boring. Out of my FiiO m11 it got more power and sounded much better. The low end was somewhat weaker on the m11 but that’s the case for all my headphones when they get plugged into the m11. While I had the FiiO m15 it definitely got close to desktop setup(smsl su-8/sh-8 combo) and it had more than enough power so it was a good combo. Out of the schiit heresy it felt a lot like the m11 and sounded a little on the clinical side. It felt a tad more congested as well at times. Out of my smsl sh-8 I got a lot more low end and really clean mids and highs. Definitely my favorite setup and combo for the Aeon closed RT. The heresy and sh-8 were fed sound from the smsl su-8 dac.

Balanced vs single ended- All I have to say on this matter is that using an adapter and doing my best to swap between SE and balanced is that I noticed a slightly wider sound but not by much. Even then it’s hard to tell if that’s really the case since it’s hard to volume match on the fly while swapping between two jacks. I like balanced because you get more power but it’s always hard to tell if a difference is made sound wise without having two of the same headphones and two of the same amps. These overall like some power though they don’t need “full watts” to make them sound good.

Overall thoughts
Well for $500 as of this review this is a steal. These are super lightweight and so comfy. I can and do get caught up listening for hours and never feel fatigued. The cable is not my favorite but converting a cable to the hirose connectors they use is not only easy, the connectors are sold for a really good price on DC audio’s website. While the Aeon closed RT won’t be taking on the $1000 plus headphones I do think even if these were the same cost of the original aeons $700 price that it would still be a full recommendation from me. I haven’t heard many sub $1000 closed planars that I would say come close to these in terms of comfort and sound. These are a great revival of the original Aeons IMO and I’m interested to see what the aeons 2 provide over these sound quality wise. Great job to the team at Dan Clark audio and I look forward to what new goodies they come out with down the road! Thanks for reading!