Headphoneus Supremus
FiR Audio M5 (1YR Update): My “If I Could Only Have One” CIEM
Pros: God-tier performance on everything – checks every box, best bass ever, full-sized performance, low volume audiophile capable
Cons: Monopolizes your ear time making you less patient with other CIEMs
**UPDATE 07/30/21**
After listening to my custom FIR M5 for a year now, I had to come back and update my review to give the M5 the full credit that it deserves. The FIR M5 is absolutely my “If I could only have one” CIEM. After a little background, I will break down why I feel this way.

BACKGROUND: Those that know me know that I have had access to most of the top-tier universal and custom IEMs from the top global manufacturers in the industry for over the last decade through the tours I manage and the reviews that I write. My personal collection of both custom and universal IEMs is extensive as you can view in my HEADFI and AUDIOTIERS signatures which are just a sample of what I have, not all are even listed. I also have extensive conversations with my membership and the top reviewers in the industry and the M5 has not only surprised me but has received the most universal phrase of any IEM I have toured or reviewed. Everyone that I have spoken to without exception has referred to this CIEM as a very special top performer regardless of their signature preferences.

MY TIERING SYSTEM: To break down my experience, I categorize the various top-class CIEMs I hear into 3 tiers – GOD-TIER for the rarified few – the best of the best, TOP-TIER for those that are examples of the best-in-class, and SECOND-TIER for those that are wonderful for specific use cases but not quite best-in-class. Below that, I typically respectfully decline to review. Most are at the lower tiers with a maximum of 5 in GOD-TIER where I place the M5. This list continues to evolve as the bar continues to rise where my previous favorites get pushed down the list. All these CIEMs are over $1000 and can be as high as $5000 now with the price climbing so these are not cheap products and a $5K CIEM is never 5x better than a $1K CIEM so your mileage may vary.

WHY THE M5: As a GOD-TIER IEM, the M5 not only is one of the best of the best but it checks every box. It is in the top three in all my use cases and performance categories across the board and is the top performer in many. Yes, if we get granular there are other CIEMs that can beat the M5 in some performance categories, but for my preferences, the M5 comes out on top for these reasons:
  • Signature: To be fair, the M5 caters to my preferred signature as discussed later. It is onstage and intimate, it is full-ranged and full-sized staging, and it is the most realistic bass I have heard. Others may have other preferences, but the M5 nails mine. When I go to other lower-tier options, I feel like something is missing so the M5 get most of my ear time.
  • Custom Fit: The M5 is a GOD-TIER option that is offered as a custom which is critical to getting the best fit possible. In fact, it is, unfortunately, the only GOD-TIER option that offers a custom option. While some can get full fidelity out of a universal format, I cannot and always deal with compromise. Those universals that fit me the best still require me to stay perfectly still to enjoy them so they only work with a specific at desk audiophile listening use case. However, most of my listening is active and on the go or laying in bed which is not optimal for universal fit.
  • Performance: There is not a performance category that the M5 is not in the top three and in many cases it is the top performer. Most IEMs focus on an area that makes it unique, there is always an area of concern – scales up but not down, requires lots of power, poor isolation, etc. The M5 allows me to enjoy it in all use cases and seems to not have an “Achilles heel”.
  • Ear Protection: FIR’s 3rd generation atom pressure release system offers a pressure-free listening experience that allows me to turn the volume up without hurting my eardrums. I have tried many companies' pressure release options with varying degrees of success – most having a downside that reduces performance in some way. There is typically a tradeoff of bass performance, detail, and soundstage that you can have two, but not three. The M5 atom system is the best I have heard offering a cavernous, out-of-head soundstage experience and wonderful bass performance while retaining a very tight note – no compromise.
  • Low-Level Listening: The M5 is one of the few that offers stellar low-level listening performance. The presentation holds tight at low volume allowing me to listen at low volumes at night without compromising performance. The full delicate detail remains even when the volume is down, it just moves me off stage and into the second row offering great performance while listening in bed.
  • Scales Up and Down: The M5 sounds as wonderful on an iPhone as it does on a high-end system. Yes, it does scale up on my best equipment to a remarkable level, but on the road, with my iPhone, it offers top audiophile performance as well on the go. There is more performance out of an iPhone than you can actually hear given the background distractions when moving around in day-to-day life or while working out.
  • Price Performance: Believe it or not, at $2800 the M5 is somewhat of a bargain. If you can afford it, the M5 is on the low side of pricing in the GOD-TIER category offering a high price to performance ratio. Relative to its $5K peers, I am more comfortable taking the M5 with me out of the house and to the gym which I would never do with a $5K option. This gives me more versatility to use it as I would like.
For all those reasons and more, I award the FIR M5 with my “If I could only have one” award as well as the GOD-TIER achievement award.

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Full Review​

  • Pros: God-tier performance on everything – checks every box, best bass ever, full-sized performance, low volume audiophile capable
  • Cons: Monopolizes your ear time making you less patient with other CIEMs
My quest for the best CIEM started 6 years ago, cumulating into building a full audio tour membership club to be able to feed my addiction with endless tours. Over the course of these tours, I have learned that best is subjective…it depends on your use case. My use cases are on the go, exercise, low volume listening, optimized high-end desktop sources for audiophile best, bass fun, detail retrieval, DAP pairing, genre pairing, etc., etc., etc. This has left room for a number of CIEMs in my portfolio, a whole lot of CIEMS. Each has been optimized with cables and source and genre. Some scale-up, some scale down, some are very specific for a use case.

Then came the Fir M5. It scales up and down sounding wonderful on my iPhone 11, yet scales even higher on my Burson C3R. It sounds wonderful with all my genres, offers bass fun, excels at detail retrieval, and even works great for noisy gyms. It is my “if I could only have one” CIEM. Since receiving it, it has gotten most of my ear time as it is easy to use. My others may scale higher by a little but require a lot of effort to get there with high-end cables and sources and they cost a lot more. The full-sized sound allows me to hear fine details intimately even in a noisy room. As you can tell, I am very impressed with my custom M5.


My CIEM Prospective​

For those that don’t know me, I have been hosting numerous TOTL CIEM and cable tours on Head-Fi in the US for the last several years now including most of the top manufacturers ranging from moderately expensive to very expensive options. This has allowed me and my tour participants access to hear some of the most incredible mobile audiophile equipment in existence. Even in the few years that I have been managing these tours, I have seen significant advances in technologies and performance to the point that it is rare to hear any product at this level that I do not like. They are all different in signature appealing differently to different people, but they are pretty much all very good at this point. So when I am raving like I am about the M5, this is in the perspective of most of the top-tier IEMs from the last 6 years. To learn more about me, you can follow me on HEADFI where I go by username BARRA or you can go to my tour membership site where you can even join my tours.

What is the Deal with Fir Audio​

While Fir Audio seems to have come out of nowhere and reached the tops of the performance charts overnight, there is a lot of history behind this achievement. The founder, Bogdan Belonozhko, is one of the Belonozhko brothers of 64 Audio fame. He brings with him the knowledge of 64 Audio performance, but with a twist. With his M5, he has created a tribrid CIEM before 64 Audio has come out with theirs. If you have heard any of the stellar 64 Audio products, then you probably have high expectations for the Fir Audio lineup and based on what I have heard and the reviews I have read, Bogdan has delivered. This is why I reached out to set up a tour so we can all hear them for ourselves. If you are interested in joining the tour to hear for yourself, go here:

The FIR Family​

As seen in the graphic below, the FIR family is 4 IEMs strong and they share a family sound. As you can see from the configuration chart, they all share that same dynamic driver that brings the signature to life.


From my FIR tour, I was able to listen to all these siblings side-by-side and found quite a value in the lower-priced options for those that cannot afford the M5. Here are my early listening impressions to offer you a comparison:
  • M5: Nailed it! This is that big bassy sound that i have so been craving. Yes, it rivals my EE LX as the bass king with a different take on bass. My first impression is WOW as it is that different than my other CIEMs in a good way. The sound stage is huge, with players/instruments huge as if I was there. While this is not as warm of a signature as my LX, it is more intimate and close-up for in-your-face fun. Yet it checks all the boxes for audiophile performance. This reminds me a bit of the A18 with the M20 module, but with better bass and lighter treble. I Will be doing a full written and video review on this one so hang tight for comparisons and deeper insights.
  • M4: The M4 is extremely close to the M5 with more of a treble presence. All the bass is there, but the treble stands out more with more splash, sizzle, and air without ever being harsh. But going back to the M5, it is not missing any of this detail, just not as pronounced and more integrated. This is a great option to save some cash for treble lovers that want that M5 bass.
  • M3: Again, that same bass driver is delivering the goods with a well-defined house sound. The M3 is close to the SQ of the M4 but set back a little maybe one section back. While I prefer the M4’s more intimate signature, the M3 is pretty darn close in sound and retains the M4’s larger treble presence.
  • M2: This was my biggest surprise and the greatest value play in the lineup. It has all that bass goodness the rest of the more expensive models boast which makes this lineup so much fun. However, the signature becomes more intimate closer to the M4 than the M3. While I do think that the M4 and M3 have more detailed performance, you would not notice without an A/B sampling as it feels like I am splitting hairs.
End-to-end all models have that same wonderful bass driver that is very distinctive. The M5 stands out as more refined using the EST top-end drivers, but there are many that prefer the BA treble splashiness and could prefer the M4. The M2 is remarkably close in signature to the M4 with a little less detailed presentation and screams value. Don’t just take my word for it, join the tour and see for yourself.

Overall, I have to say that we are dealing with another CIEM manufacturer that is continuing to drive the top-tier bar even higher. Yet they have carved out a new signature that is unique to the other manufacturer’s offerings that will definitely drive some solid sales. This lineup is a must-hear if you are considering a CIEM purchase.

Tour Kickoff Video​

To give you a better perspective on the family, here is my FIR tour kickoff video that shares the universal tour kits and my experience with them.

The Custom M5 Unboxing and Impressions Video​

To give you an understanding of the M5, I felt it is best to start out with some video so you can see it for yourself.

The Order Process​

Having ordered a number of CIEMs, the lack of ordeal here is a great thing – boring is good! The entire process can be handled online offering WIZIWIG support on the custom designer. The material options are good, and the process is easy to follow end-to-end. Best of all, there is no language barrier nor time zone issues. Over the years, I have had a number of less than optimal experiences so having a seamless experience like this is wonderful.

Here is an image of what I designed:


Here are the results:


Fit and Finish​

My ears have a weird bend in the inner ear that makes listening to universal IEMs…difficult. This means that I often have to cup my ears or stay perfectly still once I have achieved a perfect seal. This has moved me to mostly choosing custom fit in-ears. This is a process of going to an audiologist and having impressions made – per FIR Audio’s specific instructions – then hoping that the impressions are good enough to use once received. Having found a good local audiologist, I am most certain of a good impression, but there is also a bit of craft and secret sauce from the side of the CIEM manufacturer that can vary the results. For example, Empire Ears creates a smaller mold that is easy to insert while Vision Ears offers a larger mold that creates a suction when inserted or pops when removed. Both work great, but the tighter the fit, the more the frequency range is expressed, and the loser, the more comfortable but susceptible to outside noise. FIR meets the middle ground with a nice fit that is easy to insert but creates a nice suction for full-range sound.

The finish is outstanding. As you can see in the picture, it is a polished gem and there are no sharp edges anywhere. The “ATOM” module you can see on the face requires more finesse than the typical faceplate, but they offer an outstanding finish. This is a medium-sized mold so it is compact and easy to insert and has a recessed port with a screen to offer wax resistance.

ATOM (air transferring open module)​

64 Audio being one of the originators of the air module design, it comes as no surprise that Bogdan has brought his own version of the technology to his company. These modules in all their formats and under all the different names all have a single purpose, to protect your hearing. By releasing some of the pressure in an optimized format, your eardrums don’t take a beating that has always been a concern with in-ears. My M5 came with three modules – black, grey, and gold.

In practice the modulation of the air pressure does two things for those CIEMs that offer it:
  • Sound Modulation: Many manufacturers including FIR offer a variety of modules that offer different sound enhancements. Some are closed offering a larger bass, while some are very open offering more of an out of the head experience.
  • Higher Volumes: Due to the pressure system, volumes can be increased offer many advantages such as a fuller sound without discomfort.
The ATOM XL 4pk is an offering of additional modules that can be used to shape your sound to your liking.


From FIR:
“atom (air transferring open module) is the 3rd generation module technology that was specifically designed to give the user maximum control with front vented In Ear Monitors. Boasting a bass tolerance of 1/2 db make these modules the most advanced way of fine tuning that perfect sound signature you’re looking for. A smaller filter design reduces the air volume in the module chamber which can have a positive effect on sound presentation. The 4 pack set comes with an assortment of +, N, -, O (plus, neutral, minus, open). Durability was a high priority with the atom design. Filtering using a precise medical grade tubing allows for a consistent production process. atom is also immune to shock from accidental drops and even humidity. Isolation levels vary among the modules relative to the bass leak.”

ATOM Specifications:
  • (+): Isolation: 17db, Bass: 2db @ 20hz
  • (N): Isolation: 15db, (m15 equivalent)
  • (-): Isolation: 13db, Bass: 2db @ 20hz
  • (O): Isolation: 10db, Bass: -4db @20Hz

M5 Tribrid Specifications​

As can be seen in the FIR family graphic, the 5 in M5 stands for 5 drivers – ESTAT-high, BA for high, mid-high, and mid, then a dynamic driver for the lows. It is a true tribrid. Here is what FIR has to say about the M5:

“The M5 is the showcase of all the best technology FiR has to offer in the IEM space. Sporting a dynamic driver for lows, 3 balanced armatures for midrange and highs, and an electrostatic driver to assist the treble reproduction, the M5 maximizes its driver count to present an effortlessly massive sound, with shocking clarity and extension on both ends. We’re also proud to be the first in the world to implement the electrostatic drivers, in addition to all the other drivers in the M5, in a tubeless design, paired with the 3rd generation atom pressure release system to provide the M5 with a cavernous, out of head soundstage and a pressure-free listening experience that is well suited to all professional and audiophile use cases.”

My Thoughts on the Configuration:
  • DYNAMIC BASS: The interesting part for me in this configuration is the dynamic bass module. The M5 is holding the top spot for bass with the EE LX, but both are very different in presentation. The LX is warm and laid back while the M5 is tight and huge without stepping on anything else in the frequency range. There is a clarity that comes with the M5 that you don’t ever hear with bass this big. No, not fart cannon big, but full-sized audiophile speakers in a $100K setup big. We get a full-sized foundation immediately so that the other frequencies are not strained when raising the volumes to reach realistic sizing. I did my best to get some clarity on how this is possible, but all I got from Bogdan was that this is a 10mm dynamic driver with some secret sauce tuning. This is a bigger driver than all the other top-tier CIEMs with the exception of the Noble Sultan that shares the same size with different results.
  • ESTAT: The ESTAT is here to stay. Having heard a number of implementations, when done right, there is an exceptional clarity that cannot be matched by the older BA sound. The goal here is butterfly wings delicacy with oozing detail that if done wrong can be too sharp or even bright. It is fair to say, FIR got it right. Balancing out the huge audiophile bass with butterfly wings delicacy and detail is quite a feat.
  • DRIVER FLEX: None. There seems to be a lot of conversation about this topic in reference to dynamic drivers so I thought I would confirm that I have not heard any driver flex with any of the FIR family lineup. Perhaps this is due to the ATOM modules managing the air pressure.

Other Specifications:
  • Range: 10hz – 20Khz
  • Impedance: 6.8ohms

The FIR Family Cabling​

FIR went proprietary RCX on the cabling. While this is a bummer for us cable rollers with an investment in high-end cables, the cable is great and I have not felt an immediate need to upgrade as I have with many others. While I will explore a little cable rolling later and I am likely to pick up an adapter available from FIR later to enable further cable rolling if I ever get adventurous – for now, this cable is good enough.

The value of two-pin is that it is widely accepted, but I also have issues swapping cables too much as the hole that you insert the cable pin into does wear out and stretch creating a significant problem down the line. Therefore the MMCX and the RCX were developed to create a better connection as well as the ability to swap out cables without damaging your CIEM. However, the 2-pin seems here to stay which is moving us toward adapters such as this RCX 2-Pin Adaptor available on the FIR website. What is troublesome though is the price. At $79, it is a deterrent for many…at least until the stock cable breaks.

My experience with the RCX cable connector is actually quite good. It clicks on with a good click giving you confidence that you are securely connected and remains tight. This and the MMCX are preferable to me if I wasn’t already stuck with 2-pin on my entire CIEM collection.

The M5 Sound​

When describing the M5 sound, the first thing that comes to mind is its full-sized presentation even at lower volumes. The second is that wonderful audiophile BASS richness brings the sound stage to life…that being there feel. Then finally, the in-your-face detail from the mids offering butterfly wings to thick textures is what makes it so enjoyable. While most CIEMs with bass this big would be on the warmer side of neutral, the M5 has an intense clarity to it with large staging that allows the details to take center stage.

  • BASS: The M5 is my favorite bass CIEM along with the EE LX. The EE LX is set back, laid back, and calm where the M5 is more center stage, on your feet, and dancing. This bass starts big at low volumes so that it is present for my nighttime listening offering a much richer sound than I can get from my other CIEMs at that volume. The ATOM pressure regulation makes it easy on the ears as well so again, this is a wonderful low volume CIEM that I prefer for my nighttime listening. My other CIEMs need too much volume to sleep comfortably to reach that level of performance. Going to full-on EDM, that 10mm driver pounds and has become my favorite EDM CIEM. Scaling up to my high-end desktop equipment such as my Burson C3R or my Eddie Current ZDs, the bass gets even better with a tighter and more powerful response with a larger soundstage to enliven. Again, this is the top-in-class bass which I will compare later to other top-tier options.
  • MIDS: Given my description of the bass, you would think this was a warmer driver that would sit on the mids, but no, the mids are what I like so much about this CIEM. At low volumes, the voices are all full-sized and upfront and center making them rich and offering gobs of in-your-face detail. In sizing other drivers, I find that the mids fall apart when getting to the right volumes, however, here on the M5, turning up the volume just scales up the details as you would expect from the top-tier audiophile equipment. As mentioned, the mids offer butterfly wing details as well as thick textures at the same time with the separation to hear it all simultaneously.
  • TREBLE: Going back and forth between the M5 with the ESTATs and M4 with the BA drove treble, the BA treble sounds splashy while the ESTAT treble sounds delicate and airy. While the BA treble offers that SHHHHHHH, the ESTATs can bring out the most delicate textures. In fact, the ESTAT implementation with the M5 is so good, it doesn’t call any attention to it. What it does is layers the presentation with additional detail in the mids and the bass. It is so good that the treble goes somewhat unnoticed. With the drier treble, there is a lot more room in the soundstage to bring out the more important details which the M5 does in spades.
  • PRESENTATION: The M5 feels like it is either front row or on stage in its presentation. It is a very intimate affair. I hesitate to say intimate as it is not closed in as that may imply, but more like you are in the middle of a larger theater on the stage in the VIP section.
  • SOUND STAGE: The stage is large, but it is deeper than wide giving the impression that it is narrow. But if you listen, it is not narrow at all, just very layered with the Important voices up close and personal. However, there is a large ambiance, that sucks you in with access to other things going on in the room, as you might hear in live performances. There is clarity and space between voices that allows great staging. I wouldn’t go with a black background with this CIEM as there is such rich depth and depth cues that sometimes offer a holographic feel.
  • SCALING DOWN: My M5 sounds wonderful on my iPhone. Going bike riding is a real treat. I am amazed at how well it scales down, even better than my A12. This is a big driver to sound so good on so little power. I typically find that dynamic drivers don’t do so well on low-powered lower-end gear like the iPhone.
  • SCALING UP: My favorite source for my CIEMs is currently my Burson C3R which takes them to the stratosphere in performance. If I want to know just how high they can fly, the Burson is my go-to setup. In comparison to the much more expensive ERL or THUMMIM or the WRAITH, SULTAN, the M5 holds its own. The ERL peaks out with great DAPs with its BA design and can beat the M5 at that level, but the M5 peeks higher on the Burson where the ELR falls apart. The THUMMIM can beat the M5’s performance on the Burson, but cannot keep up using DAPs as a source. The ERL and the THUMMIM are almost double the price. We will all have varying opinions at this level as they are all stellar and offer different takes on a presentation that will appeal differently to different people, but I think we can all agree that these mentioned CIEMs are top of the class and the M5 belongs here. In scaling up, it is the power that the M5 gobbles up to produce exotic performance and the Burson offers it in spades at 7.5 watts.
  • BURN IN: I thought I should mention that the M5 has benefited significantly from burn-in. While I was wowed out of the box, my review kept being pushed back as I found the performance accelerating over time. While not a total believer in burn-in, I do provide some burn-in time to all my review items to support those that do believe in it. However, I do find that dynamic drivers do benefit from being exercised to loosen up the driver. For example, the iPhone was a loser at first as there was too much driver flutter. After a month, the M5 became my best pairing with my iPhone 11. I also found that the M5 scaled up with the Burson easily with its greater grip of the driver believing that was required, but it turned out that this exercising of the driver was all that was needed. It took a month of continual usage before I felt that there were no longer gains.
  • HISS: Given the low 6.8-ohm impedance, I am often asked about hiss. However, I’m probably not the right person to ask about hiss as I am over 50 and cannot hear treble like I used to. Regardless, to my ears, there is no problem with hiss on my WM1a, H2, Calyx M, iPhone, or Burson.
  • PAIRING GENRES: Given its intimate nature, it is surprising that the M5 is actually very good across most genres. It is great at EDM as you would imagine, but it is also really great across the newer fresher sounding pop, instrumentals, easy listening, classic rock, and pretty much everything else that I throw at it. Specifically, it is most amazing at live, guitar-focused, or bassy music with incredible texturing and detail. If you would want to sit at the front row of a performance, then the M5 is the right CIEM for you. However, orchestra and opera where you may prefer to sit in the upper balcony to take it all in and enjoy the wider soundstage, the Legend X might be the better choice.
  • ADJUSTING TO ESTAT: There is no ear fatigue with the M5. I bring this up as it took me three solid days of listening to the Valkyrie and the Wraith and their ESTAT implementation before I got used to the ESTAT sound. However, as mentioned earlier, going between the M5 and M4, I am an ESTAT believer and will likely favor ESTATs going forward.

Optimizing and Pairing​

The M5 sounds great out of the box even before burn-in and the cable is wonderful. However, audiophiles such as I rarely leave good enough alone. After a couple of months of stock setup, it was time to stretch the M5’s legs. Here is what I did as described below.

Optimizing Cables

In the end, the stock hybrid Effect Audio cable that came with the Valkyrie was the best pairing to my ears. It is a surprisingly good cable to be offered as a standard. While experimenting, here is what I found:
  • Moon Audio Black Dragon ($200): This is the thickest sounding cable of my collection and not a great match. I felt like it muddied the signature and preferred the stock cable.
  • DITA Audio OLSO ($599): This is a unique oiled copper cable from DITA that really adds to every CIEM that I have paired it with. However, it added a little much with the M5 making the bass too much and created more clipping on lower power sources like my iPhone. It also brought up the treble too much which did change the M5 to more of a V-signature with recessed mids. This is not what I was looking for either.
  • Beat Audio Prima Donna 8W ($1199): The Prima Donna is a silver alloy 8 wire cable that has wowed me on all my CIEMs offers significant clarity and additional dynamics. However, on the M5, it is just not a great pairing as it added too much treble and it muted the bass.
  • Effect Audio Eros II ($279): This is a surprisingly good stock cable. As a hybrid, it provides the best of the copper thickness and the silver detail to emphasize all the right characteristics of the CIEM. The resulting SQ is very flat and audiophile with gobs of treble and sub-bass detail providing layering for the mids. I don’t have any other hybrid cables currently to compare apples for apples so Eros II has won a place in my heart and will stay on the M5 as long as I have the adapter.
  • Stock M5 Cable: This cable was a win as is sounding as good as any of the others I tried. The only concern was that it tended to get unstranded over time making it look messy and potentially may break. However, the sound won me over, and having lost the adapter, will remain on the M5.
UPDATE 7/30/21: I ended up picking up the FIR adapter so that I could roll cables again. In the end after much experimentation, I found the Eletech Iliad to be the best pairing and is what I am using today. The Iliad doesn’t change the M5 signature at all, but just seems to allow the M5 to do everything that it does well…better – a definite level up that I can feel if I ever take that cable off. If you can try it, please do, you will not regret it.

Scaling Source

While the M5 sounds surprisingly good on everything, there is a difference in results worth discussing. Here is what I found:
  • iPhone 11: Amazon HD Music is a new app on my iPhone that has improved my sound quality considerably. From the standard Apple Music app, the M5 sounds great, but better on my better DAPs. The new Amazon app takes this up several notches and gets the iPhone closer to my dedicated DAPs mentioned below. In fact, the music discovery on the iPhone has made it my preferred method to listen to the M5 on the go. Either way, the music sounds full-sized from the iPhone, just more filled out with the Amazon app. But the dedicated DAPs are clearly better overall. I just wish that I had access to the Amazon music app with these DAPs. As mentioned above, the only weakness of the iPhone is that in crowded or dynamic passages there can be some clipping at first. However, for whatever reason, the clipping seems to disappear, and the fullness of the note returns after the iPhone warms up with 15 minutes or so constant playing.
  • Calyx M: The Calyx M is famous for its sound quality implying that the 9018 is responsible. While the stats don’t speak to this, the amp is likely to be the bigger influencer burning up a giant battery in less than four hours to meet that quality output. The clarity and transparency offered in the colder Calyx M signature offers more detail than the Sony below. In comparison, I used to like the Calyx M better than the Sony until I got a custom firmware upgrade on the Sony. The Calyx takes the audiophile performance up a notch with more and tighter detail, while Sony can actually be more fun. An advantage the Calyx has over Sony is that volume slider that allows me to perfect the volume for each song instantly and to play the M5 louder than normal for short bursts.
  • Sony WM1a: The Sony was almost sold last year as it didn’t pair well with my CIEMs until I got the new custom firmware. The new firmware now plays nice with all my CIEMs. The M5 is a wonderful pairing offering a warm performance with a nice girth to the note and more resonance and textures. The Sony with its superior battery life and UX is my go-to DAP for the M5.
  • Hugo 2: The H2 takes the experience up a notch with a better DAC and AMP. The pairing is more in line with the Calyx M but on steroids. The bass comes out more, the detail is at another level, and the sound gets fuller. However, as with the M, the H2 brings out the clarity/transparency of the M5 for more of an audiophile sound rather than the more fun Sony. The problem with the H2 is that it is a stack that is not always convenient, so this is not as normal of a pairing as the Burson C3R which takes it up another notch given the additional driving power if I have to deal with the inconvenience.
  • Burson C3 Reference: Going desktop, the Burson C3R is my favorite pairing supersizing the overall SQ significantly and in a fun musical way that crushes the Sony. It should also be mentioned that I am employing the Amazon HD Music application as a source and running it through my Sonarworks True-Fi application tuned to my HD800 headphones that work well with the M5 signature. Playing through iTunes with True-Fi turned off brings down the sound quality noticeably, so some may consider this a cheat. Regardless, the C3R drives 7.5 watts into the M3 6.8 ohms, so the volume stays between 1 to 5 out of 100 steps.


As mentioned in the beginning, I have a great collection of CIEM from which I judge all newcomers. Besides having access to all the TOTL CIEMs in my tours, I have accumulated a nice collection of my favorite including – Thummim, ELYSIUM, Legend X, A18 Tzar, Valkyrie, Hidition NT-6 Pro, A12t, Aether, Fearless S12, and others. To offer some insight into the performance here, I will compare the M5 to my best below:
  • Thummin: My other GOD-TIER IEM in my personal collection is the Thummin. I compare this IEM to the ABYSS in a number of ways. One, it has the same signature and is as exotic-sounding as an IEM as the ABYSS is a full-sized headphone. However, both require a great system to reach their full potential and can sound dull on a lessor system. When driven properly on my Burson C3R, the Thummin is the best sounding IEM that I have and yes, it does beat the M5 in this use case. However, the M5 is not far behind, even driven by a lessor setup. In this case, I would compare the M5 to the Audeze LCD-4 – another exotic headphone that is close in sound quality.
  • Sultan: The Sultan has received mixed reviews, but I personally insist that it is one of the rarified GOD-TIER IEMs when driven properly and with the correct seal. While this one is not currently in my collection, I have auditioned it extensively and will speak to it the best I can. I would compare the Sultan with the exotic STAX OO9 electrostatic headphones. The Sultan has the same ability to extract an exotic amount of detail putting it at the top of class in detail retrieval. Unlike the 009, the Sultan also has a very present and natural bass response which never steps on the detail. The 009 has nice bass, but it seems more distant with the treble more present. The Sultan is definitely treble first, but not at the expense of a fantastic base response. The M5 is more like the Thummin than the Sultan – the Sultan being a very different Audiophile signature that is all about the detail. While the M5 oozes detail as well, it is a more fun first warmer ride. These two IEMs are very complementary offering a great variety for your various genres offering two different presentations so you never get bored.
  • 64 Audio A18: The 18 was the detail monster that I used to judge all others. That being said, it has a variable signature which I have standardized with the M15 APEX module that is more analytical and my OLSO cable to maintain that performance while bringing up the bass a notch for a richer character. The 18 has a well-deserved place in the top TOTL CIEM tier and is likely to remain there for a long time. While its perfection quickly impresses, this perfection is also its greatest weakness as it can get boring over time. For this reason, I have collected a range of CIEMs that I rotate to keep my interest high. Compared to the M5, the 18 is showing its age. The M5 has that something special and is more fun leaving the 18 wanting. This is not saying that the 18 is bad as it is a great CIEM, but that the M5 is just that much greater in performance and that the bar for performance has risen in the last half-decade since I got my custom 18.
  • Legend X: My X has been my most-listened-to CIEM until the M5 arrived. Going back and forth, there are two very wonderful signatures that are very complimentary and different allowing both to sit prominently in my collection. The X takes the warmer side of the road making all music fun and rich. It makes mediocre music sound good. However, the dual subwoofers in the X are the star of the show. While they only show up when called for, my tendency is to listen to music that calls for bass when listening to the X because it is so much fun. The treble and mids and soundstage are wonderful as well reminding me of the EE Zeus when the bass is not called for so there is nothing bad to report for the X. However, the M5 bass is more intimate where the X bass is laid back and set back. The M5 is in your face on stage while the X is sitting back at the front of the first balcony. I love my X for casual listening, but the M5 is more energetic making it a great daytime driver and the X more of my nighttime listen.
  • ELYSIUM: The ELYSIUM has the best mids period with a dynamic mid-driver. It also has an EST treble set up with a single BA for lows making it a tribrid as well. However, the ELYSIUM and the M5 couldn’t be any more different. The M5 is full-spectrum, energetic, and onstage where the ELYSIUM is intimate as well, but emphasizes the mids. In comparison, I would say that the ELYSIUM is my go-to for vocals where the M5 is more fun and an all-rounder. Like the X, the ELYSIUM is more of an evening listen now that I have the M5 to take over my on-the-go duties.

Concluding Thoughts​

I find that about 70 percent of my ear time goes to active on the go listening while I exercise or run chores in or out of the house, with only 10 percent going to nighttime audiophile listening when I get a chance with the other 20 percent listening in bed. While I want top audiophile SQ for all three types of listening, for active listening I prefer a more energetic signature with more bass to compensate for the noise and distraction and also to put a hop in my step and wake me up. At night for audiophile listening, I prefer a bigger soundstage with a gentler audiophile tuning to pull out every last ounce of detail. For in-bed listening, I need a low-volume performer that doesn’t sacrifice SQ for low volume. The M5 somehow manages to offer top performance in all three use cases. This is why it is becoming my go-to CIEM for all my needs getting more ear time than any other in my collection.
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Hey Barra! I was curious what your custom fw set is on your 1a.
Very detailed review!
Thanks for sharing!
Thanks for such an extremely comprehensive review.

Your review stated “However, orchestra and opera where you may prefer to sit in the upper balcony to take it all in and enjoy the wider soundstage, the Legend X might be the better choice”.

Could any of the Atom Modules improve the M5 and make it more acceptable for orchestral music?


Reviewer at Ear Fidelity
Fir Audio M5 Custom
Pros: Fantastic tuning
Very natural vocals
Build quality is perfect
Lots of great design choices
Good cable
Great case included
Atom modules
Impressive tech inside
Very open sounding
Cons: Not cheap
Fir M5 is a flagship IEM by Fir Audio, that’s based in Vancouver. It is a trybrid design using 1DD, 3BA, and 1EST drivers per side. Here’s a review of the custom version with ATOM modules, costing $2948.


Fir Audio is a company founded in 2018 by Bogdan Belonozhko and Daniel Lifflander in Vancouver. Even though the company is relatively new, its founders carry almost 10 years of experience in the audiophile and pro-audio industries. Bogdan is by no means a newcomer to the market, as he has been the CEO of the vastly popular and successful 64 Audio.
At CanJam Singapore 2019, Fir Audio have announced their first line of in-ear monitors, of which the M5 is the top-of-the-line model.
After the success of their first lineup, they quickly launched their newest baby – the VxV, which we have reviewed here.

We’ve also done a video review of them:

As you can read and hear, we really enjoyed our time with the VxV, as it provides a fatigue-free, pleasant, and easy to listen to sound signature with great technicalities. Also, it’s one of the cutest IEMs ever created with its bunny design, so that’s also a plus.

Today’s review is quite different though, as the M5 is the TOTL model costing almost $3000. It has to be something more than a great tuning and cute looks to provide a great value in this very high-end market segment. Let’s see how it scores.


That’s what I call a nice packaging.

Okay, let’s start with the unboxing experience. The first time I saw the box of the M5 was a really pleasant surprise. It looks even better in person than in the photos. It has a space-ish theme with the signature bunny ears on the top of the box. The gray and gold color scheme looks sophisticated and high-end, and it’s always a great thing to see in such an expensive product. After all, you’re not only buying the IEMs, you’re getting the whole experience of dealing with a luxury product.

On the back of the box, you’ve got an information about your specific unit. Here you can see the serial number, model of choice, and your name, which is a nice touch. The Atom-X stands for the Atom modules, which I’m going to cover in the “Tech” segment of this review and trust me, it’s really great. Also, the “ROOTS RUN DEEP” sticker on the back of the box, going around its side is a winner when it comes to fun and sublime story-telling of the product, and I’m really into this kind of stuff. I’m the guy behind the story of the model “Pneuma” of the Polish IEM manufacturer Lime Ears, back when I used to work for them. Not gonna lie, Fir Audio really got a very talented team when it comes to marketing, story-telling and those little things, which make you enjoy the product just a little bit more. Cool.

Roots Run Deep.

Let’s open the box and see what’s inside, shall we? And as you might have expected, good things don’t end here, quite the opposite actually – it only gets better.
You’re immediately greeted with your IEMs on the display, and that view got me, but more on the actual build of the IEMs later.
There are other things in the box except for the earphones of course, and it all makes for a great set. First, you have the warranty card and user guide, which will help you get a snug fit of your new CIEM. On the back of the user guide, you’ll find a message from Fir Audio:

“Born out of a love for bringing great products to professionals and enthusiasts, as well as a desire to conquer new frontiers in the real of in-ear monitors – the M Series’ IEMs were designed as a result of seven years of experience and experimentation, bringing the next generation of earphone design to you. “
With love,
Fir Audio Team
It’s really hard not to like their attitude, not gonna lie. As I said earlier, when you’re going high-end, you’re not only buying the product, but the whole experience, and Fir Audio really got it right. But hey, that’s not all, you’re in for a next treat, which is the carrying case.
Burgundy is one of my favorite colors, and I was pleased when I saw this beautiful, round leather case. What’s even better is that you can get your name engraved on top of it. It says Ear Fidelity on mine – a personalized product from top to bottom.

One of the best cases in the game.

Inside the case, you’ll find your ATOM modules, and a cleaning tool to keep your CIEMs nice and clean. It smells good and is roomy enough to comfortably use on the daily basis, without the risk of destroying its content. It’s yet another quality addition, which you’ll be really glad to have.

Build quality and comfort​

Hello there.

This segment of the review will cover my specific pair of the M5, so it’ll be highly subjective. When getting a custom IEM from Fir Audio you have a lot of designs to choose from, so feel free to go wild and create your own, unique design.

I went for the “Black Opaque” shells which are matte to the touch and the “Dark Horse” faceplates with gold logos. I was tempted to go for an all-matte design (yea, you know me, minimalism…), but I decided to add a little something in form of the textured and rich faceplates, and boy oh boy, that really turned out perfectly.

Subjectively, these are the most beautiful IEMs I’ve ever seen in my whole life, the design creator really doesn’t make its justice in showing how mind-boggling your CIEMs will look when they’ll arrive. Well, that might be a good thing actually, because you’re in for a treat.

Apart from the design itself, the build quality is simply put – perfect. The matte shells are absolutely flawless, and the transition between the shells and the faceplates is sublime. You’re getting absolutely no imperfections or air bubbles. Considering the price you’re getting the most out of it when it comes to design and craftsmanship. Also, as far as I know, Fir Audio is the only company to offer matte shells in Custom In-Ears market, and as their trademark, they really perfected it. Oh, and all of the design customizations come at no extra charge – sweet.

Speaking about the comfort, as you could expect from the Custom Earphones, these are (once again) perfect. Snug fit, secure yet absolutely no-fatiguing. The isolation will depend on your Atom Module of choice, with Red isolating the least, and the Golden ones isolating the most. With both golden and silver modules, you’re getting a very, very high level of isolation, to the point of not hearing a thing while listening to music, even in very crowded and loud places. That’s also very desirable when you’re a performing artist on the stage.

Last but not least, you can choose between two different types of connectors – MMCX and RCX, with the latter being recommended by Fir Audio. I went for the MMCX though, as it’s more flexible when it comes to different cables of choice. Thanks to that I’m able to use the stock cable, my Cross Lambda Future-Jr, and Nostalgia Olorin depending on the result I like to get. What’s surprising though is that the CIEM market is dominated by 2-pin connectors, and you won’t find that option here. I personally don’t mind, as I like the MMCX connectors and I haven’t had a single thought of regret.


You’ve got plenty of choices when it comes to the cable as well.

When it comes to the cable, yet again you’ve got a lot of options. You can choose the termination from 13 (!) different options, the cable’s color, whether you’d like memory wire or not – basically everything you’d think about. I went for the “Whisky” color, 8-wire cable terminated with the 3.5mm straight connector.
Even though the cable is 8-wire, it’s not too thick nor too heavy, quite the opposite actually. It is very comfortable to wear and use, and its quality is really good. Of course, you’re not getting the audio performance of a really high-quality aftermarket cable as for example Erua Tawa, Cross Lambda Future-Jr or Nostalgia Olorin, but as far as the default cable is regarded, you’re getting a high-quality wire to begin with. If you’re going high-end you’ve most probably got a high-end cable to use anyway, and if you don’t…well, you most probably should get one.


Sophisticated when it comes to the build – impressive when it comes to what’s inside.

Fir Audio M5 sports some impressive technologies inside, but let’s start with its driver configuration.
It uses a single dynamic driver for the low frequencies, 3 balanced armatures for mids and highs, and an electrostatic driver for the treble. Tribrid designs have been more and more popular lately and for a good reason – it offers the most out of every single driver type. The dynamic driver is unrivaled when it comes to punchy, physical and rich bass reproduction, balanced armature drivers handle the midrange in a very coherent, natural and technically superior fashion and the EST driver is well-known for its fantastic sparkle and detail on top.

It doesn’t end the though, as Fir Audio is the first company in the world to utilize all three driver types in a tubeless design called Direct Aperture Acoustics, which makes for superior sound reproduction. Instead of using the sound tubes, every driver has its own place in the shells, which gives the M5 that very natural and roomy sound signature.

The M5 is rated at 6.8 Ohm which is very low, and there are no official values when it comes to their sensitivity.

Last but certainly not least – the Atom modules. They really deserve their own paragraph, so here we go.


4 different ATOM modules – 4 different sound signatures.

Let me put that straight – get the ATOM modules, for $149 extra you’re getting so much flexibility and the ability to tune the M5 to your preferences. It’s totally worth it, especially having in mind that it costs less than 10% of the total price of the standard custom M5.

Each module has a different rating of noise isolation, and these are as follows:

Yellow: 17dBSilver: 15dBBlack: 13dBRed: 10dB
That means that every single module will change the sound signature of the M5. The SILVER module is the “stock” that is the closest resemblance of the universal version of the IEM, and the one I’m using the most. It sounds the most natural and balanced, with rich and textured bass and quite a lot of headroom. It sounds just right and most refined, but it is my subjective take. You can definitely see them as a “safe” choice that’ll give you the most natural voicing, timbre, and slam, without sounding too extreme as the YELLOW ones. I would compare these modules to the likes of Campfire Solaris 2020 or the Unique Melody MEST.

The BLACK modules are lighter on the bass and more spacious sounding, but it also loses that warmth of the midrange, especially in the lower part. While it may be great for many, as it still provides a balanced and highly resolving character with very wide staging, I personally find it a hair too thin sounding, and the upper midrange gets a little hot with certain pairings, especially with poorer mastered music. Its tuning is shifting towards the likes of Final A8000 or Vision Ears Elysium, without those trademarks of both being the incredibly fast transient response of the A8000 or that ethereal, very spacious sound of the Elysium.

The RED modules are unfortunately my least favorite. Unfortunately, because I absolutely love how my M5’s look with those inserted. Nonetheless, they offer the least amount of bass, the broadest soundstage, but they do sound harsh on the upper frequencies on not perfectly mastered tracks. This is highly subjective, but I try to avoid thin sounding audio equipment at all cost, being into thick and moist midrange presentation. The M5 on red modules are extremely fast, resolving and glassy sounding, but it certainly doesn’t suit a lot of people. If you’re into that kind of sound signature though, you might find it great. It’s hard for me to find an IEM that I can compare this sound signature to, but if I had to pick one, I’d say Final A8000 and Campfire Audio Ara with less bass presence and less body to the midrange.

The YELLOW modules are my second favorite to the SILVER ones. They are my special weapon when I’m in need of that extremely thick, bassy and punchy sound, and I do get that kind of vibe from time to time. These modules have the least amount of air, the smallest soundstage and the most delicate treble response, but you’re getting a fantastic, bold bass reproduction and highly saturated lower midrange, which’s really favorable for male vocalists in my opinion. I can compare this module to Campfire Audio Dorado 2020 for example, with less presence to the lower-treble and slightly less “in your face” sound.

To summarize my choice of modules – I tend to use the SILVER ones the most often, and by quite a margin actually. They sound the most refined, natural they are really great all-rounders. I believe they should be the top pick for most. Nonetheless, I tend to switch to the YELLOW ones when I’m into more pop-oriented, bassy and fun music. They provide the most amount of air pressure going into your ears, the biggest bass and the treble that is quite forgiving even for badly mastered tracks.


How does all of the above affect the sound – that is THE question.

Fir M5 is often described as a natural and fun-sounding IEM with great technicalities. At its asking price, it surely has to perform like a TOTL product to be a viable choice in the high-end market segment. Let’s see how it performs. The sound description is based on the SILVER ATOM module, unless it’s stated differently.

Let’s start with the bass. It is rich, bold, and punchy, having all the advantages of a good dynamic driver. Don’t expect it to be bloated or poorly controlled though, as it clearly is not. The definition and extension are clearly top level and it can compare to the best in the business when we’re talking IEMs. It is NOT a neutral and flat bass response though, that’s very important.
The low frequencies are actually consistent with the rest of the frequency response – fun, rich and forward. That’s really nice to see, because there are many high-end IEMs that are neutral, flat and they all seem to sacrifice fun for the ultimate insight and neutrality.
The M5 is made to have fun with, to be pulled into a music show. What’s important though, its bass response is nowhere as “crazy” or “over the top” sounding as the likes of Polaris 2 or Dorado 2020 by Campfire Audio. If you want an ultimate, fun bass – these two should be on your shortlist to get. If you crave bold and musical bass that is at the same time outstanding when it comes to the detail, texture and control, the M5 is probably one of the best IEMs you can get, regardless of the price.
Let’s take the “Random Access Memory” by Daft Punk as an example. The mastering of this album is just perfect, as it is one of the best sounding records in the history of music. That means that it sounds good on (almost) any good audio equipment, but it really shines on great ones. And yes, it is an experience to listen to this album on the M5, thanks to its fast, full-bodied and rich bass response.
Let’s switch to the track by 21 Savage, called “A lot”. This song is full of that thick, bouncing, and deep bass rumble. The M5 handles this track perfectly, with superb vocal presentation and that marvelous bass. It’s good to pair it with something like iBasso DX220, which itself is capable of producing a great, textured and bold bass response. Also, going balanced gives us that additional texture and control.
When changing to the YELLOW module the bass gets a significant boost in presence but it loses this great control. It starts to bloat into lower-midrange a little bit, but in music like this it might be quite desirable. Post Malone approves the YELLOW modules…at least it sounds like this, with improved presence and physicality of the bass when listening to his albums.

iBasso DX220 + Fir M5 – FUN.

The midrange sounds very natural and rich on the M5. It is slightly warm and definitely romantic-sounding with great lushness and richness that compliments the bass response just perfectly. The vocals are quite forward on the SILVER modules, while not being overly exposed or too big. It handles every instrument flawlessly, resulting in a very realistic and enjoyable timbre. Also, the amount of details and the resolution of the sound are next to class-leading. What’s the most impressive is that the M5 somehow combines that rich and moist vocals with sounding very open and accurate.
The midrange has a certain characteristic thing to it that I can explain as “flowing”. It’s simply so sweet sounding that you’ve got a feeling that it flows into your ears in a very delicate manner.
This midrange somehow reminds me of the Solaris 2020 by Campfire Audio, which are my go-to IEMs when it comes to that romantic and moist midrange presentation that I personally adore. Both M5 and Solaris are full-bodied and rich sounding, and while being quite similar in terms of timbre, the Fir Audio flagship is more detailed and its resolution is definitely higher.
Thanks to that kind of presentation, I have a great time listening to SYML, Lunatic Soul or Chris Jones, which highly rely on that creaminess of the vocals. It is a true fun provider, but it offers a reference-quality sound performance at the same time.
Let’s get into female vocals, and I’m (as usual) going to point out Stevie Nicks from Fleetwood Mac as an example. Her voice sounds forward, and it vibrates in a way that gives us that “exciting” feeling when listening to her. Switching to the BLACK modules gives us that additional presence in the upper-midrange, which leads to her voice sounding more open and transparent. While she begins to sound more prominent and shimmering, it’s important to pair the M5 with a properly tuned source. The Cayin N3Pro handles that situation better than the DX220, thanks to its warmer and darker sound signature when using the tube or ultralinear mode.

The treble keeps the fun sound signature of the M5. It is extremely clean and transparent sounding, thanks to the inner construction and lack of sound tubes coming from the EST driver. The overall presentation is very vivid and open, and the M5 has one of the best resolutions in the game. While it sounds inspiringly coherent and clean on both SILVER and YELLOW modules, switching to BLACK and RED sacrifices that richness for the presence of the treble. BLACK modules remind me somehow of the Final A8000, but it’s not as fast and physical as the Japanese flagship.
Let’s go back to the SILVER modules though, as these are the best when it comes to the treble response. It maintains that excitement and presence while sounding extremely clean and rich.
The song “The Expert” by YELLO is a great example here. it sounds open, shimmering, and detailed but there’s no sign of stiffness nor harshness. The combination of balanced armature and EST driver for the high frequencies sounds like a sweet spot between extension and overwhelming presence.
The treble of the M5 also does improve the soundstage significantly, as it’s greatly extended and neutral. It helps with filling the soundstage with lots of air and music plankton.
Another great example is “After Lifeless Years” by the British band Sylosis. It’s a fresh take on thrash/melodic death metal, with a lot of things going on at the same time. There’s a certain aggression to this song that is nowhere close to being easy to reproduce by any IEM. Luckily the M5 does its thing here, and it retains that aggressive and in-your-face treble presentation of the song, while sounding extremely clean and natural. No peaks, no harshness, but a lot of shine and presence. Thanks to that the M5 is an outstanding IEM for metal genres, as it combines that thick, rich sound with an energetic and superbly clean treble response.

Matte black + Dark Horse faceplates.

Now onto the soundstage. It is definitely not the deepest or the widest sounding IEM I’ve heard. Its strength is in the accuracy on the other hand. While it maintains to create a naturally extended stage, it’s nowhere close to the level of Unique Melody MEST. The latter provides more spacious staging, especially to the sides. When it comes to imaging though, the Fir M5 retains its status as one of the best in the market. It creates a very holographic and accurate soundstage that sounds natural and just proper.
“Hell Freezes Over” by The Eagles is my favorite live performance ever recorded, and the Fir Audio Flagship provides us with one hell of a show. From the audience clapping, all the way to filling this giant venue with musical pulp, it clearly sounds refined and lifelike. Every single instrument (and there are quite a lot of them on this record) is presented individually, and you won’t be having any problems focusing on the sound source of your choice.
Another song that I use to test the staging on a regular basis is “Dusk” by Edison’s Children. Once again the Fir M5 gives us a spacious and accurate soundstage that is filled with music. You’ll be hearing sounds coming from different locations and you won’t have any problems pinpointing any of them.
Now into the most important record when it comes to the soundstage, and my personal favorite album of the 90s. “Amused To Death” by Roger Waters. This album is filled with sounds coming from every direction and the M5 really shines here. Dog barking behind you, radio playing on the far left side, Roger himself walking around you and saying “I can feel it” and “My mind is going”. While listening to this album on the M5 you’ll be having a tough time believing it’s not a binaural record – it’s that good on the Fir Audio Flagship. Brilliant.


VS Vision Ears Elysium

Vision Ears Elysium

This comparison seems very rational. Both the Elysium and the M5 are Top-Of-The-Line models promising the best performance. Truth is – it’s hard to be more different than these two.
Fir Audio M5 is definitely more fun, richer and warmer sounding of the two, by a mile. Its vocal presentation is thicker and, thanks to that, more natural. While I’d give an edge to the Elysium in terms of the soundstage size and its sprightliness, its bass response is just butchered by the M5. The latter hits harder, is far more natural and fun sounding, while the Elysium seems boring and thin in comparison. I know that not everyone likes that extra bass presence, but when we’re talking about the overall bass response, the M5 is far superior to the Elysium. Single BA vs DD, there’s no comparison, simple as that.
The Elysium is generally thinner, less exciting and airier sounding of the two. If you’re into that kind of presentation and you’re okay with an underwhelming bass response, then I can see you choosing the Elysium over the M5. If you want more presence to the music, warmer tonality and just a ton of fun, the M5 is by far a better choice.
Choose the Vision Ears flagship if you’re into a very spacious, fresh and ethereal sound and you avoid metal/pop/electronic/rock music. If you’re into classical music – you most definitely will like the Elysium more, if you’ll accept its rather poor bass performance.

VS Final A8000

Final A8000

First of all – The Final A8000 is very, very tip dependant, so it’s important to state that this comparison is being done using the stock Final E tips.
The A8000 is definitely faster and more vivid sounding of the two, with more upper-midrange presence and faster transient response. On the other hand, the M5 is more full-bodied, warmer and it has more natural vocals.
The string action and the overall presentation of an Acoustic Guitar are the trademarks of the A8000, and it’s really hard to beat. It provides more “metallic” and sharper sound of the strings, which is very desirable in this regard. Fir M5 is better suited for metal, rock and rap music thanks to its boosted bass presence and more melodic, warmer vocal delivery.
While both go head-to-head when it comes to detail retrieval, the A8000 has a slight edge when it comes to micro-details, and the M5 is slightly better with macro-details and the overall texture.
While the M5 is more punchy, rich and melodic sounding with a romantic midrange, the A8000 is more lively, vivid and transparent. it reminds me of a battle between an American and Japanese tuning, which surely is apparent here. Up to your personal taste, you can’t go wrong with either of these.

VS Unique Melody MEST + Erua TAWA

Unique Melody MEST

The Unique Melody MEST is definitely one of my favorite pairs of IEMs ever. Together with the Erua TAWA (review here) it costs just about the same as the M5. The Fir M5 is definitely better built and it has a better unboxing experience, but it’s about the sound, isn’t it?
Both share many similarities, as they do sound fun, forward and rich. The MEST takes a lead when it comes to the detail retrieval and the size of the soundstage, while the M5 has a more sophisticated tuning and it somehow sounds more open. Yes, that might seem strange, as the MEST has a wider and deeper staging than the M5, but somehow it feels more compressed when it comes to the air around the instruments. The Fir M5 might not be as wide or deep, but it uses the space it has just perfectly, sounding more open and transparent of the two, but it’s not a day and night difference for sure.
As I stated in my review of the MEST, it has this interesting thing to it where it seems that it adds that slight and pleasant vibration to the sound, which might be the result of using the Bone Conduction driver. The M5 is slightly warmer and more “flowing” sounding of the two when it comes to the midrange, with more transparent and neutral treble response. Overall, if you like the MEST, you’ll most probably love the M5 with the SILVER APEX modules.

VS Campfire Audio Ara

Campfire Audio Ara

These two are quite different. While the Ara goes for a very neutral, flat, and detailed sound, the M5 is way thicker, warmer, and more spectacular sounding. They go head-to-head when it comes to detail retrieval and imaging, but they are surely tuned for different people. The Ara would satisfy everyone who’s into that reference-like, neutral and uncolored sound, while the M5 is more natural and richer. I definitely prefer the M5, which gives me much more fun while listening to music, without actually sacrificing anything regarding its technical performance compared to the Ara. It’s way more expensive, sure, and you’re just able to hear that.

VS Fir Audio VxV

Fir Audio VxV

Even though these two came from the same team of people, they are actually nothing alike. The VxV is, as Fir Audio (accurately) called them – Everyday carry. Easy to listen to, fatigue-free and very safe when it comes to the tuning. The M5 takes everything to the extremes when compared to the VxV. It’s warmer, bolder, more open and spectacular. It also leads when it comes to detail retrieval and imaging, which shouldn’t really surprise anybody. If you want that kind of calm, delicate and neutral sound performance, then you’ll be very happy with the VxV. If you’d like more excitement, richer and just a better sounding IEM though, go for the M5 and call it a day, it’s worth the upgrade and that extra charge.


Fun providers for a true audiophile.

Fir Audio M5 is a complete package. The unboxing experience is great, build quality and design possibilities are both astonishing. When it comes to the sound, it offers a superbly rich, romantic, and fun sound signature with excellent technical capabilities. It comes at a high price, but seeing how great everything about it is executed, it’s certainly worth it.

Highly recommended.


Gear used during this review for the sake of comparison and as an accompanying equipment:

  • Headphones – Unique Melody MEST, Campfire Audio Dorado 2020, Ara, Solaris 2020, Final A8000, Cayin Fantasy, Vision Ears Elysium, Fir Audio VxV, Hifiman HE1000se, HEDDphone, Hifiman Ananda
  • Sources– Cayin N3Pro, iBasso DX220, SMSL SU-9 + SH-9, LittleDot MK IIIse, Cayin C9, JDSLabs ATOM,
  • Cables – Nostalgia Olorin, Cross Lambda Future Jr.
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Headphoneus Supremus
FiR Audio M5: At what point...
Pros: Fit
Fabulous sound
Detail, clarity
Price (when compared to other TOTL)
Cons: Not mine
Price (when compared to what some have)
Not mine
Not much else
FiR Audio M5 ($2800): At what point...

4.75 stars



I sit here having downed a full pot of Joe on my (well deserved) day off from school (tooting my own horn). Listening to My God from Jethro Tull through the Little Dot mk3 se (fabulous btw) and the M5, I peruse the latest HeadFi cards on this cold rainy Friday. Skimming to the Erlkönig Dragonskin “covers” for the shell, I realize it’s a shell cover they are offering...for $366usd. Moving to the Abyss AB-1266TP Phi TC video review, I notice the title “most ridiculous headphone ever” and go back to the homepage. I may watch it later to see what that is really about...

Munching on my Honey Nuts and O’s with 2% as well, my Aussie patiently waits for me to finish as I scribble this dribble, so she can “clean my bowl.” I am hit with the comment on the VE page of “excess capitalism” and “you have to enter a draw for the right to purchase?” commentary... This gets me thinking about all of the “luxury” items I have had pass through this prairie state abode of late. I regularly carry the TOTL’s I’ve had around to school, providing that chance to “listen” for 30-40 minutes on my plan as I grade/plan/email/etc. I do find that I get more done listening to music, as the distractions outside my room are minimalized. But a simple $25 IEM can do the same thing. Or can it? Some of the products to cross my path of late are simply put, incredible. And rightly so. Others reach a point where I envision some English Premier League player getting out of their Bentley listening to something extraordinary that we mere mortals cannot fathom, nor afford as their car is also skinned of chrome. My point (and especially during this time) is (and you should have already figured this out) that “at what point” is consumption considered wretched, unfettered excess?


If that EPL player is making $250k+/week to play a game we all love, who are we to decide what they spend their money on? Some such as Marcus Rashford (of the hated Man. Utd club...) who is but a lad of 22, shows his compassion for the “common man” putting many older, richer players to shame. He all but single-handedly shamed the UK government into continuing the free/much reduced food offerings to families with school children during peak COVID-19. I won’t go into your political beliefs here, but what he did is extraordinary. At 22, he gets it more than some ever will. Humble to a core, he puts his money where his beliefs are. And lest you think he doesn’t spend I would bet he does; and in fact, has many cars. But do we afford him a pass due to his philanthropic efforts? That really is not the point here.

To finish: companies are allowed to produce items, which many consider wretched capitalistic excess. Not simply because they can, but it is their desire to produce the very best they can, and then have that technology trickle down to the other models. Or to help fund efforts to continue their R&D. Here is where that excessive price can possibly be justified. By producing TOTL IEM’s (or DAP’s, etc...) companies give us the opportunity to listen to their wares and potentially purchase those same. I do not fault VE for producing the Dragonskin covers. I do not fault MMR for producing the Thummim. And I do not fault Fir Audio for the M5. They are all fabulous at what they do, and how they present their products. I do come out of this review with a definite favorite, and yes price does play a big part of that. As such, I hearken back to the old Road & Track multi-car reviews where they have the “price-independent” winner and “price-dependent” winner. I liked that and can justify this either way.

I thank @Barra for another amazing tour, with products I most likely would not have heard. This is a wonderful opportunity and I do relish the time together.


History Lesson (like Jimmy Buffet sings...)

From the website: Founded in 2018 by longtime In-Ear Monitor pioneer Bogdan Belonozhko, Fir Audio exists to offer many necessary and unique accessories for all IEM owners. Fir Audio was born out of nearly a decade of experience in designing and manufacturing custom IEMs in the great Pacific Northwest.

What that fails to say, and by reading other reviews, the founder of Fir was also the CEO of 64Audio, a company I hold with a very high regard. 64Audio models run the gamut from affordable, to wishful thinking (there’s that pattern), but as luck would have it, I have heard their TOTL IEM’s as well, and I can definitely see the “family” resemblance. Please do not take this as a slight towards Fir, it most definitely isn’t and through the course of the reviews, I do compare to a certain 64Audio model I own (and still love), as well as draw upon my experience with the Fourte and Tzar for comparative purposes. But this is about Fir Audio, and how the company has quickly (and deservedly so) risen to TOTL status with the products offered. There is no mucking about with fancy shell designs or extravagant color schemes (which again, I do not fault, and can be had here). No, here the impetus is on sound first and foremost delivering sound worth of the price or placement at the top of each segment.

I start with the TOTL, because I think the line deserves this. Call this the trickle-down effect as I will describe in the four reviews. Simple looks hide the sound inside. Think of that modified VW R32, which looks like a Golf. That is until you see its taillights right after the light turns green.


Specs (simplicity!):

Range: 10hz - 20Khz
Impedance: 6.8ohms

M5 page: Sporting a dynamic driver for lows, 3 balanced armatures for midrange and highs and an electrostatic driver to assist the treble reproduction, the M5 maximizes its driver count to present an effortlessly massive sound, with shocking clarity and extension on both ends. We’re also proud to be the first in the world to implement the electrostatic drivers, in addition to all the other drivers in the M5, in a tubeless design, paired with the 3rd generation atom pressure release system to provide the M5 with a cavernous, out of head soundstage and a pressure-free listening experience that is well suited to all professional and audiophile use cases.

I rarely get into the differences in driver count or what those bring to the table other than sound and hold to those more expert in such aspects. That hold here as well. Suffice to say, much research has been done to provide for the most opportune sound chamber and least intrusive elements of such. Said to mimic the sound of your favored properly equipped listening room, the M5 strikes me as one of the cleanest, clearest IEM’s I have heard. Right off the bat, mind you. If this is the beginning, holy buckets.


Gear Used/Compared:

Empire Ears Legend X ($2299)
Vision Ears Erlkönig ($4300)
MMR Thummim ($4500)

Cayin N6 mk2
Shanling M6 Pro
MBP/Little Dot mk3 se


Joey Alexander-Warna album and others
Mark Knopfler-Laughs And Jokes And Drinks And Smokes
Santana w/ Mana- Corazon Espinado
twenty one pilots album, Trench
Tedeschi Trucks Band
Big Head Todd & The Monsters-Beautiful World
Mark Knopfler-Down The Road Wherever
Tidal MQA

In the box/Unboxing:

Since the units all came in their leather circular cases, I cannot say what the unboxing effect was. That said, there is a nice foam insert in which the tips fit. A nice treat so that one can take multiple tips along for the ride. From other reviews, the presentation is as expected, top notch. Look for more unboxing from other reviews.


Coming from a 64Audio background, one would rightly expect there to be good on all fronts listed above. One would be right as well. Fit is on par with those. This means that the unit is unobtrusive and fits well (tip dependent, of course). Sitting near-flush in my average-sized ear, the M5 (and the others) does not bother me except for long angular nozzle. It seems to be at a bit of an odd angle for me but did not bother enough for me to grow weary of the fit. Indeed, not like the Thummim or Homunculus to a lesser degree. Using the double flanged tip I found a good seal and fit.

Build is as one would expect, too. Top notch with minimal to non-existent flaws. Since the shell cover can be customized, one would either expect a somewhat misfit with some choices, or a perfect fit. This would be the latter. The common red anodized cover fits well with no mismatched seam. Evenly matched poured acrylic shells fit the build, so to speak. There is no wild build pattern nor odd shaped shell here. Just well-made and a good, solid common fit.


Coming off the MMR duo, the expectation was one of top notch as Fir Audio tries to match the more expensive wares. One would expect and one would get that option. Upon first listen, the M5 immediately vaulted to the top for me. Matching the Erlkönig and Thummim is no small feat, but with the “heritage” of the U18t behind the making, you would expect and get exceptional detail presentation. I was struck first and foremost by the clarity. Remembering (and reminiscing of) the U18t (my favored of the two) brought back good vibes. While the Fourte probably has better resolution and clarity of that detail, the U18t was more my favored flavor. And here, that evoked the same emotive response. Extremely solid bass response, without overtaking the rest, the M5 promotes that clarity as an unmitigated, unveiled presentation. Just such a solid overall demonstration of the fabric, which drives Fir Audio, that to not enjoy it would be akin to not liking dogs in my mind. One simply cannot deny a dog that loves you. And one should not, either.

I add in the above flair, because when one goes for a TOTL status IEM, one should expect it to be a faithful companion for a good long time. And as the mids sing through Ian Anderson’s voice in My God, you get the sensation that the M5 is not afraid to get down and dirty. Just like your dog chasing its favorite ball in the worst weather. Warming your cockles as a result, the vocals sing their praise. All the while doing so without a strident or bothersome top end in the treble. Many of the TOTL of late that I have been humbled to hear tend to bother me whence the volume raises on the clockwise side of the knob. The M5 does nothing of the sort. I can raise the volume to loud levels on Jethro Tull’s fabulous BBC Blues Session rendition of Stormy Monday, with repose. And let me tell you, that song gets down and dirty just like a Saturday night fish fry deep on the bajou, complete with house band. So Much Trouble solidifies that down low sound as it should be. Presented with verve and energy, but not exuberant. Just right.

With a wide soundstage, the separation of all can be easily heard as well. Good height lends itself to a high-ceilinged sound as well promoting the layers well. To me only a bit of shortness in depth is had. But not to the detriment of the overall character. Any perceived lack of depth pretty much goes out the window on the string quartet version of In The Past, as the stringed instruments go right along with the flute. Such marvelous sounds to be heard and a succinct, precise instrumentation rounds off the character. This is a very fine unit. A surprising result for me as the character is a bit more “analytical” than my tastes prefer, but not antiseptic. Simply lovely.

Whether with the Shanling M6 Pro or Cayin N6ii, the M5 sounds wonderful and I appreciate the different character each brings. Nothing hindered or hidden from view. Complimentary. What I find across the source spectrum is that the M5 sound is quite engaging and full. There seem to be no real short comings to me, and this draws me in. One knows going in that the Erlkönig and Thummim are going to be fantastic (they are), but one can rightfully expect the same from all TOTL. And the M5 does not disappoint. Personally speaking, the M5 fits my favors more closely than either the Erlkönig or Thummim. Don’t get me wrong. If someone were to throw me a pair of either and say, “these are yours, enjoy,” I most certainly would be enjoying amongst the best I could ever have. But the M5 priced a tier down fits the bill as well or better, due to the sound AND “reduced” price.

Throwing on Albert King’s Born Under A Bad Sign, with Stevie Ray Vaughan, I sip my 5-Families Irish coffee this fine morning and turn the volume up. This is the sound, which makes for an incredible Saturday morning. Two of my all-time favorites and a good drink of Joe makes for some fantastic time. The Cayin brings Tidal Premium to light, and all is good in that time spectrum. One certainly can be afforded this pleasure at times and doing so with this combination makes the listening all the more so. Let us just say that it is a good thing I am the only one up in this week hour of the morn, for my ears are afforded the pleasure of voluminous sound. And it is good. I’ll Play The Blues For You solidifies my true respect for the M5, and I pour another. It is the weekend, and it is a wonderful way to start this off.



Fir Audio M5 ($2799) v Empire Ears Legend X ($2299):

Starting with my in-home favorite I am again reminded what intoxicating bass the LX has. Others may now in fact have “more” or “better” but it is the LX that those others owe their heritage to. The LX set the road of less traveled bass-heavy icon in motion to me, and it will always hold a special place. I currently have an Eletech Socrates enroute to add to the already fabulous PW Audio Initial Helix cable, which graces it. I do like the stock Effect Ares II but find the PW more akin to my tastes.

I do find that I have to raise the volume over the M5, making the LX a bit harder to drive. A bit narrower of stage, the LX may have met its match bass-wise. The M5 seems to be more impactful, and reach a bit deeper, but I do believe that the clarity aspect of the show is what comes out. The LX cannot match the clarity of the M5 but holds itself well when compared. I find that the mids fit my tastes a bit more, as they are slightly recessed when compared to the M5. As such, I can raise the volume a bit more on the LX. Darker of signature yet, the LX is still top notch, but you can clearly hear where the other TOTL have gone. Better clarity, a wider stage, and impactful bass make it here. That said, as I’ll Play The Blues For You comes on, I sit back and truly appreciate the near-reverbed effect of the LX’s bass. This is still a fabulous sound with which to deal as comers come and go. Still my favorite in-house, owned unit the LX is.

Fir Audio M5 ($2799) v Vision Ears Erlkönig ($4300):

When I first heard the Erlkönig, it was hands down the best unit I have ever heard. With four available settings, and clarity of God-level, it was not only the flavor of the year, but earned, deserved and worthy of that top spot to me. But it is also heavy. So much so that one cannot enjoy long sessions the way one would want. Fit is fantastic, but that heft of magical metal composition makes for a hefty unit.

I liken this to the Grand Tour episode done in Detroit. The one where Jeremy drives that killer Mustang, May drives the incredible Camaro, and Hammond the Hellcat (extra). While the Hellcat most certainly would be the top of the heap, that scene at the end where he takes forever to get the car into “race version” makes one tired. And Jeremy finally storms away in the Mustang, enjoying the wares. The Mustang would indeed be the Mustang. And the Erlkönig the Hellcat. And yes, the Thummim would be the Camaro.

At this point one must decide if you want to simply drive or change settings for a small increase of “power.” Here, in this review I simply want to listen. Plus, I have always been a fan of Mustang’s.

Both are incredible, but one costs 35% less without the fiddling as well. I can think of many household “upgrades” where that extra $1600 could go...

Fir Audio M5 ($2799) v MMR Thummim ($4500):

38% more... Following the theme above, you must be the judge as to where the line is drawn. The Camaro is an incredible performer in that episode, and perfect for Captain Slow. But the other side would be incredible insurance costs, and the legalities of the car. Throw in that it gets GALLONS per mile when on the lead foot, and you mut decide. Plus, to me the fit makes the deal untenable. I do love the sound of that exhaust, err bass and vocals presented, but at what cost.

This makes me happy that I had the Thummim and Erlkönig first. For had I heard the M5 first, I may have been even more jaded. The law of diminishing returns most definitely holds here, and the user must decide how much candy they want to hold at one time. Solidifying my stance, the Thummim sounds fantastic, but not that much more fantastic than the M5. It is incredible when paired with the Iliad, but that raises the overall cost to $6300usd...the price of a very good used Mazda3 for your teenaged kiddos, and that to me makes it an unworthy deal. No matter the sound, which is not that much extra cost better than the M5.


Much is said about the law of diminishing returns. When one can afford a Lamborghini, one does not care. When one can afford an EleMMent Palazzo, one does not care what the cost, much the way with the Erlkönig and Thummim. Witness the latest “drawing” to get the chance to purchase a $365usd shell cover for the Erlkönig. Wretched excess galore. To get the “right” to purchase one, you must enter into a drawing. I do find that fathom of excess distasteful in this time and here is where one could truly appreciate the “affordability” of the M5. For near ½ the cost, you get fantastic bass response, vocals, which are deep rich and warm in texture and a fit that works. Unlike the others in the hyper-TOTL category.

Much like that hyper-car category has taken off (or the mentioned Detroit trio above), you the user must decide at what level insanity comes into play. There most certainly is a point even for that gold-chained Lamborghini driver where “frugality” comes in. At least one might hope so, lest they be so jaded and out of touch that they really need a reality check. But then again, when one has earned all of that, then they do have that right to choose how and what their wares be. I do not fault them for that, nor should we. But here, with the M5 a case can certainly be made for a cap on that level. A top end, which can make you truly appreciate that you have found a “bargain,” which will provide 90-95% of the sound for 150% of the enjoyment.

If I had to choose between the three, it would not even be close. The M5 would be in route to me, and perhaps another Socrates, which would make the Erlkönig and Thummim blush by comparison. Are they better? Perhaps to ears more versed than mine, and perhaps they provide that last 1% of betterness. But my point has been hit with the M5 much like it was with the LX, making it an easy decision. Cost-driven, the M5 is the clear winner. Cost-be-damned, it still comes close, and close enough for me that I would not worry should the choice be afforded me.

I again thank @Barra and also thank Fir Audio for providing their wares. They represent true value to me in the TOTL region, and moving down in their range, I can state here that the trickle-down effect will be a positive one.

Much obliged. There is a certain price at which we all call "time out," of that I would agree.

As for the Little Dot, I did, but failed to mention more than the first paragraph above. The sound was quite pleasant and I did enjoy the duo.
Will Chiu
Will Chiu
I bought myself a pair of M5 just before 2021. That is probably the only good thing happened in 2020 for me, but that is already enough. I am also a fan of Jeremy Clarkson, James May and Richard Hammond, so cheers.


Headphoneus Supremus
Pros: Bass
Cons: Midrange

From what I have heard, there have been many silent revisions of the Fir M5 and I don't know what revision I heard. This is probably the reason for vastly varying reviews of this IEM. I can only comment on the revision I heard.



Let's start with the bass. In my opinion, this is the best part of this IEM. The bass has good impact and texture. The sub-bass is thunderous. The bass is really enjoyable. It helps that the IEM as a whole is tilted to the warmer side of things. The bass is what the M5 is truly about. Good thing that I enjoyed the bass because it goes downhill from there.


The mids are in a word not resolving. There is weird haze over the midrange that makes the details not clear. The midrange is neutral with them being neither too forward nor too laid back but the haze is there which just ruins the whole experience. The midrange I would say is passable.


The Treble is the worst offender on the M5. It is trash. The Treble sounds restrained as it something is holding it back. It’s pretty slow and hefty. It just doesn’t sound effortless as good Treble is supposed to sound. This is I believe my first encounter with IEM EST driver treble and I absolutely abhor it.


Fir M5 has an average sized 3D soundstage, nothing to complain about but nothing special. The imaging is also good, it’s not pin point accurate but good enough. It also lacks some transparency and resolution especially for its price range.


Fir M4
– Now, this is what a good IEM should sound like. Fir M5 is dead neutral. It’s neither warm nor cold. The FR balance on Fir M4 is absolutely perfect. The bass is not as good as Fir M5. It’s fine with good texture but lacks the thunderous bass on the M5. The midrange is much more resolving than the Fir M5 and sounds great imo. Not the best midrange I have heard in an IEM but it’s pretty good. The treble sounds like good BA treble which is great, much much better than the M5. The treble is fast and has good weight. It is also pretty extended. The soundstage is a tad smaller and separation also takes a hit. That said, Fir M4 is a more coherent and complete IEM than the Fir M5.


Campfire Audio Solaris – Solaris is much warmer than both the M5 and M4. It has the most detailed vocals. You can really hear every little detail in these. The DD bass has good texture and tactility but lacks some impact. Fir M5 has better bass overall. The treble is fast and weighty, again good BA treble and much better than the M5. The soundstage is super wide and the imaging, layering and separation is superb. Solaris probably has the best technicalities among the 3 IEMs.


Fir M5 has been an underwhelming experience. It’s fine if it were priced at $1000 but at its current price, it’s a hard no for me. I don’t mind paying for good sound but this is not it. Again, I can’t comment on any other revisions of the M5, this is strictly for the unit I heard.

Equipment used to test:

  • Oriolus Stack (BD20, BA300s mkii, BA20)


100+ Head-Fier
Pros: Good balance between the bass, mids and highs. Treble isn't too present, even though it's produced mainly by an EST. Comfort and look
Cons: Price, bass (not the most impressive for a DD)
I had the chance to demo this IEM for about 2 weeks by participating in a loan tour, organized by a member of the community. I would like to thank him for the opportunity !

As a disclaimer, the sources used with the FiR Audio M5 are the iFi Micro Black Label and Sony NW-WM1A. I found the M5 to be fairly resistant to hissing, which makes it quite versatile with sources (big bonus if you're not sure your DAP or DAC/AMP is quiet enough). I also found the comfort to be quite good for long periods, as I did not get any pressure build up whatsoever. Stock cable is quite good. It is pliable, but not the softest. Feels good on the ears, it doesn’t itch or anything.

The music I listen to tends to be quite vast, but it mostly revolves around metal, rock, instrumental and soundtracks. Here is a non-exhaustive list of the bands I used to gather my thoughts : Dream Theater, Haken, Jinjer, Opeth, Tool, Gojira, Killswitch Engage, Lamb of God, Breaking Benjamin, Chevelle, Soen, Karnivool, Andy Timmons, Marco Sfoli, Anup Sastry, Intervals, Plini, Animals as Leaders, Hans Zimmer and Ramin Djawadi.

As for as sound goes, I think this particular IEM goes for an exciting sound signature, with decent bass (not the best, even though it’s a DD, but gets the job done). The sub bass extension and mid bass are about average for a DD (still better than most full BA setups).

Treble does not feel exaggerated, even though most EST implementations tend to have a bit too much energy for my tastes. Can definitely be a little hot for some people, but I did not hear unbearable peaks.

Mid range is quite good ! Definitely goes for something balanced. Vocals and instruments are not emphasized, they just sit a little back compared to the rest of the mix. Detail pickup was above average for a flagship. It could not keep up with some of the other models I’ve tried (namely, the Anole VX and U12t, which are both cheaper). Still decent overall, but not amazing considering the price.

All in all, I'm not sure I would recommend this IEM at full retail. The price is higher due to the technologies used (trybrid with EST, DD and BA drivers), but the actual sound does not feel improved per se. The price would be fair at around 1.7-1.9k usd, so I consider MSRP to be quite overpriced. Would probably look at alternatives from 64audio instead, although the bass response probably won’t be as good. The techs used are similar (LID, APEX, etc.), so you can something comparable if that’s something you care about.
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Headphoneus Supremus
Pros: Beautiful, natural-sounding tonality*
Good treble extension
Nice cables
Cons: Very expensive
Mediocre isolation
Channel matching might not be perfect
High unit variance
Fairly high levels of 3rd-harmonic distortion
Very low/variable impedance above 200 Hz
Not particularly ergonomic
Proprietary connectors
Ouch, that's a lot of cons. Why would I give 4.5 stars to a headphone with so many negatives? Well, because the M5 can sound absolutely fantastic. I've tried one pair of M5s that were possibly the most enjoyable in-ear monitors I've ever heard. To my ears they sounded extremely natural, with good extension at both ends - not overpowering, but just enough of a lift at the extremes that they never sounded boring.

If you purchase the universal model in the US, you can also customise your own cable on the FiR Audio website, which is pretty cool. I'd recommend memory wire in the ear hooks because of possible fit issues (more on that later). The stock cables are soft, flexible, have very low microphonics and seem to be high quality.

Some more thoughts on those cons...

Price: If there's a company out there who feels their R&D talents justify a massive hourly rate, I guess they're free to set a commensurate price for their headphones and the market will decide. But the parts that go into these headphones wouldn't seem to justify a nearly $3000 sticker price. I guess we should just be patient though... in 10 years time when there are $50,000 IEMs on the market, $2800 will look like a ChiFi bargain.

Isolation: The M5 is vented, so it doesn't offer much passive noise isolation. If sound isolation is your highest priority, you'd still be better off with an Etymotic.

Channel Matching: It was reasonable - not 100% perfect on the first demo pair I first tried - but reasonable. Note, all M5 measurements here were made on a standard 711 coupler with Cp100 SpinFit eartips. These graphs are all uncompensated:

Despite the small channel imbalance, these still sounded wonderful. After I made the mistake of pointing out the channel imbalance on this particular demo pair, Bogdan (FiR Audio owner/CEO) re-tuned them. The result was then near-perfect channel matching, but a disastrously-different FR, with a much heavier mid-bass, and a dull, muddy and pretty lifeless sound. So I guess the moral of this story is be careful what you wish for? ¯\_(ツ)_/¯

High unit variance: I expect subjective impressions of the M5 will have big variations. By which I mean even more variation than is normal for headfi. This is because of a couple of possibly not-so-good points, namely, low/variable impedance and very noticeable variations in production units. As a result, subjective opinions might not be all that helpful here. Showing a frequency-response graph gets a bit tricky too because I've heard three models that all sounded quite different:

Are you ready to roll the dice?!

One positive point worth mentioning here though. In certain IEMs, foam tips can massively damp the treble. Because the M5's bores are fairly wide, I didn't notice that much difference between silicone and foam eartips:

The M5 comes with its own proprietary brand of foam eartip. It looks like Comply, but apparently it isn't.

For whatever reason, big-name-brand companies seem to do better with QC in terms of tight manufacturing tolerances. Unit variance is possibly the Achilles' heel of the M5. From model to model, its FR appears to be all over the map. @crinacle also has several measurements for the M5 on his website and none of them match either. (Note @crinacle also shows a sizable FR spread for the other FiR Audio IEM models.) Bogdan suggested couplers and eartips might be responsible for the variations in measurements, but I don't entirely agree. I have a fairly careful procedure and all my measurements were made with the same eartips, same insertion depth, same coupler, same mic, and are 100% repeatable. From what I've seen of @crinacle's work, his measurements also seem to be carefully done and are usually pretty consistent with mine. (My measurements were made on a GRAS RA0045/40AO coupler/mic, but I also have the same coupler that @crinacle has, and measurements from my various 711 couplers match very closely for FR.) These unit variations with the M5 are real and easily audible.

Fairly high levels of 3rd harmonic distortion: At 80 dB, it's ok. Typical of what I usually see in other balanced-armature IEMs:

At 94 dB, the third-order harmonic distortion got so high in the mid-range that my measuring software quit (by default, REW stops if distortion exceeds 1%):

Does this matter? Probably not. This isn't random noise or intermodulation distortion, but harmonic distortion - in other words, harmonics that could/would exist in nature. In theory, this could change the timbre of a sine wave, but in actual music the dominant factor is the underlying frequency response, given that the harmonics of the instrument(s) are already present in the recording and the perceived FR of the headphone is almost certainly going to be deviating from flat by way more than that THD percentage anyway. Consider the irony of chasing a 0.0001% THD and then plugging those same headphones into a tube amp :)

Impulse Response: The M5's impulse response is fairly typical of balanced-armature headphones - rise/fall time is not as fast as electrostats like the KSE1500, but settle time is faster. It's also faster than a dynamic driver like the Xelento, and much faster than the planar driver in the RHA CL2:




Does any of this matter? Possibly not. Although it's intrinsically interesting, I haven't seen much evidence to suggest that we have an urgent need to be able to resolve impulses <50 microseconds apart in real music.

Square-Wave Response:

Ok, this doesn't look much like a square wave, but again I'm not convinced this has much bearing on real music.

Very Low (and Variable) Impedance: The quoted specs say 6.8 Ohm, but this is the impedance I measured, which was pretty consistent on both channels of two different sets of M5s:

The impedance is 6.8 Ohm only once you get below 100 Hz. It's way lower than that at frequencies above this, and drops below 2 Ohm in the mid-range. I've never seen a headphone with an impedance this low. Together with its variation with frequency, this definitely could have an audible effect. How many people have source devices with an output impedance lower than 0.25 Ohm? My guess is not many. I've seen mention of LID (linear impedance device?) in some other M5 reviews, but can find no mention of this on FiR Audio's website. If the M5 does have some magical device to prevent shifts in FR with varying output impedance, it doesn't seem to be working very well. Here are measurements of the exact same headphone (without shifting anything in the coupler) being driven by an RME Babyface Pro FS and an A&K Sp2000 which have output impedances of 0.1 Ohm and 1.0 Ohm, respectively:

Both these output impedances are already pretty low, but there's still more than a 2 dB shift in the mid-range. It seems safe to expect the FR to shift noticeably when moving to/from devices with larger (>=1 Ohm) output impedances.

Sensitivity: I couldn't find any official specs listed for this, but I measured it as approximately 110 dB/mW @ 1 kHz. That should mean that the M5 is unlikely to exhibit any noticeable hiss. And even if it does, that wouldn't be the fault of the M5 and you really ought to get yourself an amp with a lower noise floor :wink:

Ergonomics: If you squeeze lots of drivers into one IEM shell, you're probably not going to get something as nice and tiny as a Xelento. But why not at least make them ear-shaped and angle the nozzle up into the ear canals properly?
The fit of the M5 is ok. It's not the horrible torture that is the Campfire Audio Andromeda, but it could have been so much better - at least for my ears. I need to rotate the M5 back a bit farther and angle them out in order to get a good seal, and as a result, I've had to use a couple of funky bends in the ear-hook memory wire in order to get the cable to stay behind my ears, as the natural tendency, given the fit of the IEM, is for the wire to end up hanging next to, but not behind, my ears. If any of that makes sense?

Proprietary Connectors: The M5 comes with a pretty decent stock cable which you probably won't want to change - which is just as well, because you won't easily be able to. The M5 uses FiR Audio's own proprietary RCX connectors. I understand not everybody likes MMCX connectors, but, on the other hand, a proprietary connector makes it difficult/impossible to ever switch out the stock cable. I like the M5's connectors, but I can't see these catching on as a new universal standard anytime soon. And in the meantime, none of my existing cables are interchangeable with those on the M5. If you're handy with a soldering iron, FiR Audio sell their RCX connectors for $30 a pair; if not, you're probably not going to be doing much cable rolling.

The KSE1500 are still the most resolving headphones I've heard. However, they require a separate electrostatic amp, and I actually found the model #1 M5 to have a slightly more natural-sounding tonality. (It's a long, sad story, but model #1 got destroyed by FiR Audio and is now in that special place in the sky where all good headphones go when they die.) I suspect the only really significant metric in the KSE1500 is its tuning, but it does seem that it's difficult for other types of driver to match the treble extension of the Shure electrostats, so the M5 does a respectable job here:
The Xelentos continue to be one of my all-time favorite headphones. They're not 100% perfect though as their mid-bass is a little heavy and they have less air up-top than the FiR M5:

Does this make the M5 a more enjoyable listen? I thought the M5 model #1 was right up there with, and even slightly surpassing, the Xelentos. Model #2 - not so much. And model #3 was a disaster. Yet again, everything boils down to the tuning. Xelentos have a warmer, richer tonality, while the M5, generally, sounds more neutral or reference-like. The M5 has a tiny bit wider soundstage, but we're talking centimeters at most.

Xelentos are one third of the M5's price, much smaller, with much better ergonomics and standard mmcx connectors. One word of warning though - there's now a plague of very authentic-looking, but poor-sounding, counterfeit Xelentos all over the internet. I would consider it risky buying Xelentos these days from anywhere other than Beyerdynamic.
The new kid on the single DD IEM block is Final Audio's A8000 - a single Beryllium driver in some fairly nice-looking, silvery-polished shells. The A8000 might look a bit large and not very ergonomic in photos, but they're fairly small in real life and have a surprisingly secure fit (even more so than the Xelentos, at least for me). The buds are slightly heavy, but that's not really noticeable once they're in your ears. They fit and seal perfectly in my ears, which, for me, is an extremely rare and pleasant find. Given their appearance, I was surprised at how deep an insertion I was able to get. (<-- Insert obvious Steve Carell/Office joke here.) The one small catch though - the edges of the A8000 are razor sharp. I'm not exaggerating - the A8000 could double as a pocket knife. There's a chance this could bother people wearing them for extended periods, at least if you insert them as deeply and as weirdly as I do.

Here's a comparison of the A8000's frequency response with those of the M5 models I tested:

The A8000 does get remarkably close to the Harman target in the bass and lower mid-range. Note, however, that it's not quite as close to that target curve in the upper mid/lower treble regions:

Jude's measurements (originally shown on his NY CanJam preview video) suggest a closer match to the Harman target throughout the entire frequency range, but note that Jude's measurements were made on a GRAS RA0401 coupler - a coupler that's designed to intentionally damp the half-wave resonance of the ear canal. The RA0401 coupler is an interesting device for design purposes, but not as useful for knowing how IEMs will actually sound in your ear. I've made previous comparisons of the two different types of GRAS coupler, and it's always the same story: the canal resonances are, as intended, pretty much missing from the frequency response: ( Running a frequency sweep, I can clearly hear resonance peaks at ~5.5 kHz and, at only a slightly lower amplitude, at ~8.5 kHz (the fact that I hear the canal resonance at a slightly higher frequency than that indicated by the 711 couplers is probably because of the deep insertion I was able to get with these buds). Try listening for yourself with a frequency sweep. I bet you'll hear that ear canal resonance which the RA0401 coupler suppresses.

What this means to humans with ear canals is that the A8000 might be perceived as a little lively in the lower treble. (Note that the M5, even measured on a standard 711 coupler, does not exhibit any significant narrow-band resonance peaks.) Overall, the A8000 is still a really great headphone - it just leans a bit brighter than the M5. The A8000 uses standard mmcx connectors, and at $2000 (USD), it is cheaper than the M5. My preference could easily change with source material, but if I was forced into one of those awful Sophie's choice scenarios, I'd go for the M5. But honestly, I think most people would be perfectly happy with either.
I realize I'm probably in the minority here, but I don't understand the hype around these. I find their uneven frequency response to result in something that sounds quite unnatural:

They just don't have the realistic timbre and clarity of the M5. They're also pretty large, heavy and not very ergonomic, so fit issues are a serious possibility. I don't think these justify their price. The $250 FLC8d sound better to me than the IER-Z1R.
There's a family connection here between 64 Audio and FiR Audio and I've heard a rumor that the M5 was designed to have a similar tuning to that of the Tia Forte. I'm not sure I see or hear that though. The Tia Forte has a bit of an uneven bump in its mid-range. I don't know if that's the reason its sound never really impressed me, but its 600 Hz bump makes any comparisons with other headphones using normalization around that frequency look rather weird. I definitely preferred the model #1 M5. However, a word of warning... Can you hear the subtle difference between the original Tia Forte and the new Tia Forte Noir? If so, then beware, because that difference is far smaller than the unit variations I've heard in the M5:
The Legend X is my favorite Empire Ears product. They are really bassy headphones, but they're one of the few IEMs that handle the bass properly, i.e., they have more sub-bass than mid-bass. The only reason I don't own the Legend X is because they're large and don't fit my ears well :frowning2:
After many years of ownership, and despite no longer being "new" or a "flagship", these are still going strong and they continue to surprise me with new tricks, e.g., with eartip and filter modifications. Even with the Trishd mod, the SE846's upper treble does roll off a bit earlier than that of the M5, and the M5's dynamic bass driver has a bit more punch. But the SE846 is one third of the price and offers really good passive noise isolation:
A $250 IEM can't possibly compete with the big boys, right? I would disagree. The FLC8d is right up there. It even has tuning options via replaceable filters and it costs less than the price of the FiR Audio M5's cable. Compared to the M5? That's a tough call as I've heard M5 models that sounded much better than the FLC8d and other M5 models that sounded worse:


This is the most difficult part of my review. Can I recommend the M5? I don't know. Most of the negative issues listed here should be relatively minor to most people. The main issues are: 1) whether you can get the M5 to seal and stay in your ears, and 2) if you're lucky with the tuning on the unit you receive.

Unit variance with the M5 can be huge, so even if you've heard a demo pair you like, you're still going to be taking a bit of a gamble on a purchase. Compound this with the uncertainties in tuning any CIEM, and I could never recommend a custom M5. (But then I don't recommend a custom anything.) I'd strongly recommend prospective universal M5 buyers to contact FiR Audio and ask to audition the exact pair they intend to buy. If that's not possible, I'm not sure I could recommend the M5. I've now heard three M5 models: one sounded phenomenal, one sounded good, and one sounded pretty muddy. That kind of loose manufacturing tolerance is not ideal at any price, but it's a poor show at $2800. In fairness to FiR Audio, unit variance of other headphones probably isn't well documented. It's common knowledge that reviewers tend to get A-stock, and actual buyers are often left with somewhat lesser-sounding production units - and in most cases, those buyers probably never ever find out. This might even be the root cause of many disagreements on headfi, where two people think they're discussing the same headphone :wink: If you can demo an M5 with the option to buy the exact unit that you heard and liked, then I would go for it :)

Update (Feb. 2021): Comparisons against the M2, M3 and M4 can be found here:
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Awesome write-up. Curious to hear these now


Headphoneus Supremus
Pros: FULL range sound, deep bass with impact, extended highs without shrillness, dynamic
Cons: I prefer an MMCX connector for cable rolling, some prefer not to have LID, bass can be heavy handed for some

Disclaimer: I am not affiliated with FiR. I received the pair of M5 I listened to as part of the FiR tour.

Introduction: I will apologize, sort of, right now for this review being very similar to those I’ve posted for the FiR M3 and M4. I hope it’s not too boring and repetitive because there is a method to this madness. My theory when I started was to use a similar format for all my FiR reviews in hopes of making it easy for you to perceive the similarities and differences I heard. As you know, I’ve only had IEMs for a few years. Here I am, looking for an upgrade. My current long-term reference for in-ears is the Campfire Audio Lyra II. I like the overall balance of the Lyra II, but enjoyed the bigger bass of the Vega, though I only got to listen to those for one evening. I have been looking for an upgrade ever since discovering I’m an emerging bass-head.

Design: The M5 is a five- way design: dynamic woofer; balanced armature midrange, mid/high and tweeter drivers and an electrostatic super- tweeter. I’ve been intrigued by hybrid designs ever since I bought my Campfire Lyra II. After having the M4 for a bit more than a week, I am curious to find out what the electrostatic driver adds to the sound.
As with the M3 and M4, the M5 housings are generally triangular, and fairly deep. The sound pipes are fairly long. Both of these traits are good for me. Triangular housings seem to fit my ears pretty well and the long sound pipes will let me get deep insertion. I’ve worn ear plugs at work for years, so I am used to jamming things as far in my ear as possible. Shallow insertion feels unstable to me.
The housings are nicely made: smooth with rounded edges. They might be die-cast, but I’ll bet they are milled. I don’t see any fasteners holding the face plate to the housing. The outside looks powder coated: satin black for the body, light gold for the face plates. The M5 have vents below the RCX connector as the M3 and M4 do.
M5 2 small.jpg
The M5 housings are well crafted and understated, like an English luxury car. They are not so sculpted as the Meze Rai Penta I also have (more Italian looking), and cleaner than the Campfire Audio Lyra II. The latest IEM to arrive in my house is the 64Audio Trio. The Trio is slimmer than the M5, and its corners are more rounded.
Meze Penta shells.jpgMeze Audio Rai Penta
Lyra shells.jpgCampfire Audio Lyra II

Packaging: I still can’t make a comment about the “retail” packaging from FiR as I received my set as part of a tour. Truth be told, I don’t much care about packaging anyway. Sure, it’s nice to see a fancy box, but I’d rather have my money put toward the IEMs themselves; or at least good tips. Honestly, after I put the box in the closet, the next time I’ll see it is if I wrap it up to mail it to the new owner.
M5 4 small.jpg
What’s in the box? What came in the box sent to me was a large (for IEMs) metal can with a screw-top lid containing the M5 and a 5-pole (Sony) cable. I’m glad I had some ear phones from a friend who’s a fan of the Sony connection, otherwise I wouldn’t have had an adapter. Would have been my fault, it’s not like FiR failed to disclose which cables were shipping with which tour IEMs. Also in the box was plastic baggie with some extra tips. The metal can is lined with foam, and has a cleaning brush in the lid. But, it’s too big for daily traveling.

RTFM: No literature came with the tour pair of M5. That’s good, I’d have to spend audition time to read it, anyway.

  • IEM Connector: FiR Audio use their RCX connector. I won’t quibble about whether it’s mechanically superior to an MMCX. What I do know is I have a few cables with MMCX connectors I can’t use with these IEMs, and I’ve never worn out an MMCX connector. Perhaps musicians do. I hope FiR will offer MMCX as an option for those of us who aren’t hard on their gear. The cable provided came with “RCX angled black” connectors at the IEM end. I didn’t like them at first: they didn’t fit my ears or with my glasses well. I did get used to them, though. Still, if I were to order a pair of IEMs from FIR, I’d try their “RCX Barrel” connector instead. Perhaps a minimalist strain relief and no memory wire that allows the wire to be wrapped over my ear as closely as possible? I’ve also seen some FiR IEMs provided with RCX and clear over-molding that looked smaller than the black connectors…
M5 3 small.jpg
  • Cable: The FiR cable provided with my tour pair is really thin and flexible. It comprises eight wires, twisted, not braided. Microphonics weren’t a problem for me. No microphone is offered, which is fine by me.
  • Source connector: The tour M5 cable was supplied with a straight 4.4mm penta balanced connector.
  • Tips: I skipped the tips provided with the tour M5. After my experience with the M3 and M4 I skipped right to my Spin Fit 240. I may have tried my RHA dual flange briefly, but the Spin Fits stayed on pretty much constantly.
  • Fit, Comfort, Isolation: I like the shape of FiR’s universal housings. The triangle shaped housings fit my outer ear reliably. I never had any trouble with either M5 ear piece, and the Spin Fit 240 gave me a consistent seal and secured them well. The FiR universal shells don’t nestle into my outer ear like my Rai Pentas, or the qdc Anole VX I had a chance to try briefly (the Anole is shaped similarly to a custom shell, no trouble with fit for me, it was great), but I didn’t have any problems with them either. Choosing between universal and custom would actually be a problem for me. Isolation, with a good seal, is good. I had no problem sealing out the chatter in the group office space I’m currently working in.
M5 5 small.jpg
What I Listened To: I like simple and compact, so I used my AK70 MkII. As far as music, I kept the SD card from my M3 and M4 auditions, so I listened to mostly the same songs. I did add a couple new songs, though.

Soundstage: I am not a sound-staging aficionado, at least not when it comes to head phones. Like the M4, the footsteps at the beginning of Chris Rea’s “Auberge” started way outside my left ear, crossed the stage and stopped outside my right ear. Also, “Sea Wall” from the Blade Runner 2049 soundtrack filled my entire head with sound. Most other recordings I listened to weren’t quite so dramatic. The M5 soundstage generally stayed between the face plates. I had a few new songs on my audition SD card. One is “Adventures in a Perambulator” by John A. Carpenter. Instruments had good separation across the width of the stage and various instruments could be heard left, right, top, bottom and various locations in between. I didn’t notice much layering or depth, but I think that’s me not the IEMs. While I don’t notice much differentiation in height or depth, big orchestral pieces sound similar to what I hear from my normal seat at our concert hall: 20th row center. It could be I am not good with spatial cues. I won’t argue with anyone who tells me I’m full of it here.

Highs: When I received the M5 I dove right in and just let my audition list play. As with the M4, I spent a lot of time comparing the M5 treble of the Trio, since the Trio’s top end is one of my favorite aspects of its sound. I came to this conclusion: the Trio are sweet. By that I mean extended, airy, light, never sibilant, delicate. The M5 I believe to occupy a middle ground between the M4 and Trio. The M5 are not sweet, either, but they have more capability to show finesse than the M4 can. I don’t think the M5 treble is peaky, it doesn’t get fatiguing to me. It certainly isn’t hot or shrill.

“All Right Now” from Doc Powell’s The Doctor is again a good track to compare treble. The cymbals are recorded with intricate detail and no sibilance. The Trio present an amazing amount of detail, shimmer and resonance (that’s not really the right word), while the M4 presented amazing energy and laser-like clarity. M5 has most of the energy of the M4 but lacks a bit of the Trio’s detail. That may sound like a bad thing but I’ll point to Eva Cassidy’s rendition “Blue Skies”. Her voice is front and center, clear and soaring, just like it should be. Right behind her, though, are the cymbals keeping time in bell-like fashion. “Chitlins Con Carne” from Stevie Ray Vaughn’s The Sky is Crying proved its worth again. The cymbals are almost the only treble in the track and easy to focus on. What a treat through both the M5 and Trio.

You’d think New Levels New Devils by Polyphia and “Bandenburg Concerto 1” by J.S. Bach would have only being on my audition list in common. Not so fast. Both allowed the M5’s articulation to shine. In the Bach it was the harpsichord I focused on; in Polyphia’s song “Saucy”: all the weird snaps, stops and starts. Fun stuff when you’re listening to an articulate transducer.

Mids: Every guitar, acoustic or electric, I played through the M5 sounded great. I didn’t listen to any of my Pete Fountain or Don Byron, but clarinets in orchestral settings sounded rich and mellow. Emmylou Harris’ voice on “Deeper Well” was worn and expressive, and Julia Fordham’s voice during “Porcelain” is smooth and clear. While I was enjoying my brief time with the Anole VX I noticed something in Frank Sinatra’s “One For My Baby” (Only the Lonely) I hadn’t noticed before: the first pitch of the first word of nearly every verse is noticeably more baritone than the rest of the verse. It’s almost as if the Chairman’s voice needed to rev-up, make use of some low-end torque. When I listened to the M5 I heard it, not with my Rai Penta. The rest of the M5’s presentation is a treat: Sinatra’s melancholy tenor is smooth and perfectly clean and the piano is behind his left shoulder, I can almost see Joe the Bartender signaling him to play something “easy and sad”.

Back to the smaller scale tunes I listened to with the M3: Miles Davis’ “Half Nelson” (Workin’) was boomy and muddy through the M5. Margo Timmins’ breathy whisper of a voice floats above the deep thrumming bass in “I Don’t Get It” from The Trinity Sessions. I’ve really enjoyed listening to Henry Brant’s Ice Field. Mr. Brant throws everything at the listener, from organ to triangle. I’ve not heard this piece live, unfortunately, but I think I can hear it all. Rosin on the bows of the bassists? Check. Clinky piano right-hand during the jazzy bit near the end? Check. The celli in Bach’s Brandenberg Concerto 1, were at a non-shocking level, in balance with expectations.

OK, back to mids. For dynamics and transients: Keith Jarret’s piano (“Part II C”, The Koln Concert) revealed the M5 lower midrange, as heard in Keith’s left hand, to be full and resonant. I could hear the sound board. I could hear the notes decay as other notes were struck.

In contrast, higher up in the mid-range, the leading edges of the notes played by Keith’s right hand were emphasized. The higher notes of the piano decayed quite quickly, without bloom.

Lows: There are a couple of characteristics about bass response important to me. The first: Pink Floyd must sound good. One of my favorite things about Dark Side of the Moon, Wish You Were Here, The Wall, et cetera is the bass wraps its arms around you and holds you close. It’s warm and smooth and wonderful. The other is: I would love to find a head phone able to reproduce “It’s For You” by Pat Metheny Group (As Falls Wichita, So Falls Wichita Falls) properly. I am beginning to think this is a fool’s errand, there just isn’t enough volume inside ears to allow Steve Rodby’s bass the room it needs to bloom.

M5 bass is deep and powerful, obviously from the same family as the M3 and M4. Sometimes it’s overpowering. I didn’t remember the M3 bass overpowering any songs, but perhaps I was having too much fun with them. There are a few songs which just sounded wrong to me with the M5: “Deeper Well” (I can’t believe I wrote that….), and “Better the Devil You Know” by Me and That Man are a couple of examples. In the former the bass sounds separated from the rest of the music and interferes with the vocals sometimes. In the latter, bass is clear, but so big it makes the song sound bloated and too big. I find it very disconcerting and there aren’t very many songs I listened to which displayed this characteristic. Even stranger is the coincidence that on my audition SD card “Deeper Well” is followed almost immediately by “Easy From Now On” which sounds nearly perfect to me. Go figure.

I don’t want to dwell on those few songs too much, though, because the M5 bass is so good most of the time. So let me not make a mountain out of a few freakish mole hills. Electronic music: Blade Runner 2049 fills my head with pulsing sound. It’s menacing and intimidating. Resonance and hall sound? I’ll refer back to Henry Brant’s Ice Field. The bass drum filled the right side of the hall with booms that nearly echoed and the skins tympani “rippled”. No mere thuds and thwacks here. Sure, poor recordings sounded muddy and indistinct; but good recordings allowed the bass to shine through and often provide more than a droning basso-continuo foundation to the music. I much appreciate that. Rush’s “Limelight” is a good test for this. Neal Peart’s kick drums vie with Geddy Lee’s bass to be front and center in the rhythm section. The M5 do a good job, better than the Rai Penta, Trio or Anole VX, of keeping the two separated.

Oh, “It’s For You”? Nope, I still need a subwoofer in the living room. But a little less with the M5 (it is a smooth rumbling bass riff, after all).

Gestalt, Zeitgeist, Fahrvergnugen (and other German words meaning “the whole enchilada”): Some of this belongs with the conclusions, but here we go anyway. I’ve already noted my discombobulation with the M5 bass. I won’t belabor that point any more. On to some general comments about the M5’s overall behavior:
  • Some of my favorite songs sounded muddy through the M5. James McMurtry’s “Choctaw Bingo” didn’t surprise me all that much, but “Another Brick in the Wall Part II” sure did, it’s the MFSL remastering after all. Damn transducers with reference level resolution: if there’s mud in your recording, they’ll let you hear it.
  • The M5, like the M3 and M4, encouraged me to turn the volume up. But it wasn’t as necessary: I found the M5 to provide a satisfyingly full sound at fairly low volume (less than 50% of full volume on my Mk70 II), while I often cranked the M3 and M4 (and Trio) to 66% of full volume. Richness and fullness scaled with volume, though. The M5 was merciful also, not punishing me with ringing ears or fatigue.
  • The M5 were more relentless than the M4, but not so much as the M3 (or LCD-X). The M5 gives an energetic performance, with lows and highs on an equal footing with the midrange and ample dynamics and articulation to propel the music forward, urging you to listen.
  • qdc Anole VX: A quick note since I had a quick listen to these. I can see why some who have commented the M5 sound is V-shaped. While I was listening to the Anole VX I thought to myself, “If this is linear then the M5 is definitely V-shaped. But then, if the M5 is linear, the Anole is mid-centric.” Vocals were more up-front through the Anole, but at the same time, compared to the M5 the bass and top register sounded quieter. My metal-head friend, who likes leaner bass than I do, preferred the Anole VX to the M5 (and M4), so there is that. The Anole VX does present vocals in a beguiling manner…
  • 64Audio Trio: This time I have a pair of Trio, but am missing the U12t. I’ve already tipped my hand some: the Trio has beautiful treble. The Trio also presents a bit more detail at the top end than do the M5, though the gap is somewhat narrower. I was a bit surprised by this. My expectation was the electrostatic super-tweeter would provide something the balanced armature couldn’t (even if it is naked). In my week with both they turned out to be different means to a similar end. Great execution by both FiR and 64Audio. I didn’t find myself picking nits between the M5 and Trio in the midrange, both were satisfying. As with the M4, the M5 has more bass energy than the Trio. The M5 also reveals low frequency details with the aplomb of the M4 and Trio.
  • “Chitlins Con Carne” by Stevie Ray Vaughn (The Sky is Crying) can no longer be considered serendipitous, since I’ve added it to me audition list. But, it still proved a great way to compare and contrast the M5 and Trio. The M5 comes very close to closing the gap between the M4 and Trio by adding almost the last bit of air and sweetness to the highest highs while maintaining all that long-wavelength energy. It’s a little easier to imagine parting with the Trio and settling down with the M5. Maybe.
  • Meze Rai Penta: What I said about the Rai Penta in comparison with the M3 and M4 still stands. They don’t go as low, and lack the energy and drive of the FiR products. I spent a whole morning listening to the M5, then switched to the Rai Penta in the afternoon. I immediately missed the force of the M5 and, in immediate comparison the Rai Penta sounded muddy. But after a while I got used to the Rai Penta again and remembered the details are still there, I just had to dig for them a bit rather than having them brought to me pool-side. The Rai Penta is self-effacing, the M5 more in-your-face.
Meze Penta insert.jpg
  • Campfire Audio Lyra II: My Lyra II are a good example of what you gain by “climbing the ladder”. I still like my Lyra for all the reasons I bought them: bass, smoothness, the cohesiveness of a single driver, a bit of sparkle on top. Oh, and fit. Who wouldn’t love a little bitty IEM that just nestles in like they do? They just don’t plumb as deep or soar as high. Details are missing. The Lyra II simplify the music in comparison to the other IEMs I listened to. The lowest bass is one-notey in comparison. There isn’t quite as much body or expressiveness in Emmylou Harris’ voice, nor Julia Fordham’s. There isn’t as much air around the instruments, as much room sound. Highs are a bit muddier or splashier, less defined. The soundstage is a bit wider, extending out past the cover plates a bit, though not holographic or all-encompassing.
Lyra inserted.jpg
Conclusion: I like the FiR Audio M5, a lot. I guess that’s why I am troubled by the few examples I found where the bass bothered me. I wanted them to be a perfect match for what I am looking for. Here is what keeps me awake at night:
  • Are the M3 too much fun to ignore? I’m separated from their bass slam by over a month, but I keep referring to it like I heard it a half hour ago.
  • What about the M4? I’m sure I remember correctly they are more balanced, better all-arounders, than the M3, but how would they fare head-to-head against the M5? Is the M4 bass more controlled than the M5 eliminating the source of angst, and can that tinge of air missing in the M4’s highest register be forgiven when the Trio and M5 are available?
  • And then the outsider (at least outside the FiR family): the Trio. On top of a comfortably familiar signature 64Audio adds THAT treble. Compelling, to be sure. But I do miss the bass rising up and asserting itself as an equal partner in the music.
  • I know I like FiR products, but I don’t know yet which I’d choose to take to a desert island with me.
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Member of the Trade: Hifi-Portable
Pros: - Incredible coherency
- bass impact, wonderful mids and best treble ever
- Addictive sound signature
- unparalleled technical abilties
- Atom XL modules
- Most comfy CIEM I ever had
Cons: nothing...
Please note that english is not my native language. Apologize for the eventual spelling mistakes.

It’s always with emotion that I discover brand new ciems, this is particularly so when these are presented as a state of the art by its creator.

Bogdan Belonozhko was the CEO of the well-known brand 64 audio. In 2018, he decided to create his own brand called Fir Audio.

Bogdan told me: I wanted to bring the best from 64 audio even higher, with a whole new approach, without any compromise.

Leaving a company whose reputation is well established to create your brand is never done lightly.

I was immediately charmed by the innovations offered by Fir and its flagship model:

Here they are ! The FIR AUDIO M5 !


5 drivers (1-ESTAT, 1-BA High, 1BA High-Mid, 1-BA Mid, 1-DD Low)
Impedance: 6, 8 Ohm
Frequency response: 10 Hz – 20 kHz
Replaceable modules: Atom-XL
Tubeless Shell design technology
Removable cable "Scorpion Wire": - 1,2м / 1,6м, RCX connectors, jack-2,5мм

3 years warranty – Transfer of ownership is possible

Dealer for Europe :

After I sent my 3D prints to Fir Audio, it took a month to have the M5 in my hands. They comes in an elegant round laser engraved aluminum box, including the Scorpion 8-wires cable silver-plated copper. I immediately notice the very high quality of this cable (value is around 235 USD if sold without iems). It is a good thing when a manufacturer provides a cable that works in symbiosis with their iems. This avoids an additional investment which can be expensive if you want something very qualitative, and it allows you to experiment directly as it should be.

In the cover are installed the cleaning brush as well as the 3 Atom-XL modules that I took as an option and which allow you to modify the bass intensity.

Everything is customizable at Fir Audio without affecting the final price, from the smallest details, such as the color of the cable spliter, the connectors, but also, of course, the ciems, according to a wide choice of patterns or even the possibility to provide your own faceplate design, which I did. Finally, there is a small aluminum box containing RCX to 2 pin adapters, to be able to use all the cables on the market (in option). Indeed, the ciems from Fir are all RCX connectors, presented as a challenger for a new standard in the industry, more durable, more secure than the 2 pins or the MMCX. As far as I am concerned, it’s a great move because I’ve always found the current standards are too fragile, and aging badly, especially the 2pin which I had some bad experiences with, like damaged connectors or 2pins became loosy.

The shell as much as the manufacturing quality are exceptional. My other ciems seem a bit coarse next to it, I can immediately notice that the ear morphology is particularly respected down to the smallest details. These are the most comfortable custom I ever had, even if the design of the cannulas goes deep into the ear canal. The feeling of wearing nothing, without any pressure on the ear canal and yet excellent isolation.

It’s important to explain the three apex modules: black, gray, and gold are there to modify the presence in the bass section. Gray is the one who is on the M5 when you’ll received them and have already impressive bass section, black adds presence, while gold is the one that will produce the most impacting bass, without of course changing anything in the rest of the spectrum. And these modules really work! The difference is obvious and, after I listened the gold for ultra physical bass, with a lot of impact, I decided to change to the black modules for a while, which offer an excellent compromise, and finally, switch to the grey because the amount of bass is really already enough and impactfull, make the M5 sounding the best for my taste. The bassheads will not hesitate to taste the spectacular extreme impact with the gold modules. It's really convenient to be able to find the right level of bass you want, some people will not hesitate to change modules depending the genre or according to the mood of the day.


Fir Audio's M5s offer exemplary consistency across the spectrum. The sound is massive, physical, intense, offering a particularly immersive signature, which submerges, with natural tones, characterized by a slightly warm neutrality with a completely silent background. We are clearly on an extremely detailed / textured rendering but never falling into a purely analytical / technical signature.

The lows are very controled with a lot of body, very impactful and very clear with the grey module, even more with black module and the gold modules will gives you a big oomph effect, as the bass reflex speakers with rear vent. It’s never saturating, it is never boomy, whatever the bass intensity in the mix or volume level. The integration of the electrodynamic driver is flawless, offering with authority an impressive velocity, striking with precision and speed, revealing the least effects, reverberations, in particular in sub bass, leaving stunned: a myriad of textures.

The mids are as rich as textured, extremely natural and melodic, striking nuances, realism, contrasts, the voices are superb but also to the friction of the bows on the strings, when the piano hammers strikes, placing each element of the composition precisely in space with unusual grace.

The highs are magnified by the famous electrostatic tweeter, offering an exceptionally clear, fluid and precise rendering, with a swarm of details, making easy to hear the slightest subtleties, giving the whole spectrum a final aeration, in symbiosis with the rest of the drivers. After a good period of listening, I stayed speechless that my Unique Melody Miracle V1 sound dark in comparison… The highs go very (very) far on the M5, without ever being agressive, which for me is a tour de force. Simply fantastic.

What I notice instantly each time I listen to the M5s is the outstanding unity of the sound, the fluidity of the drivers working together, in symbiosis.

The stereo presentation is particularly extensive, even more on very rich recordings or on live performances, drawing in harmony an important soundstage both in width and in depth but also above the head, revealing the volumetric space of the recording locations (spectacular on the classical music). The soundstage of each recording is particularly respected. So it can be intimate and close sometimes or very wide and distant, depending of the mix. It’s transparent. The layering and the structure are impeccable and realistic. The chanels separation is surgical and offers ultra fast transitions. The reverberation effects resonate deeply.

The total absence of distortion invites to turn the volume knob higher and higher, dealing with the thickest mixes without ever failing, without ever aggressing, translating a dynamic that seems to be limitless. Since the cannulas go deep into the ear canals, listening can be done at low volume without losing any intensity, even for someone like me, who generally listens quite loudly. Maybe you might wonder if it can be fatiguing? Well, no, there is no fatigue despite the incredible intensity. I happened to listen to them all day without any problems.

Custom ou universal ?

I had the opportunity to listen to the universal M5, which does not allow the option of the Atom-XL. The signature will be influenced by the tips used, and in particular the material (foam or silicone). The manufacturer says that the foam provides the closest signature to the custom. While absolutely keeping most of the DNA of M5 custom, the universals do not reach their level and I can say something about 10% more performance. Not better, but more. The 2 pairs are excellent, but the custom can provide even more on everything that already makes universal M5s legendary iems. In addition, the modules really make the M5 versatile, as I explain above.

I would advise you to buy your M5 in custom and with the interchangeable Atom-XL, especially since Fir Audio offers re-molding transfer of ownership.

Cables rolling


The M5 are, despite what we can read sometimes, sensitive to cable rolling but I must say the stock cable is probably the best according to my experiences. To prove it, I did a double blind test against one of the best cables ever, the PW Audio 1960 project K 4 wires. The test was particularly well executed since I never had physical contact with the cables neither with the hands nor with the face nor behind the ears, I also couldn’t feel the weight of the cables because they were laid on a coffee table while I was sitting on the floor. There is indeed a difference in sound and the verdict was : the stock cable gives, at equal volume level of course, a clearer, more detailed and more intense signature than the 1960. In short, the ideal signature.


I have been able to test many sources with the M5. They match amazingly with the small portable dac/amp USB E1DA 9038S in IEM mode (only 85 USD), and I must say that I had to move to the very high end players to find a really important qualitative gap : the synergy seemed superb with the Lotoo Paw Gold Touch. The AK240 Redwine does not particularly honor the performance of the M5, sounding too analog / soft and clearly lacking intensity. The sound was also very pleasant with the Shanling M6 without reaching the presence of the small E1DA. The Lotoo Paw Gold Touch seems to push the M5 to their limits, an extreme sense of detail across the spectrum, adding weight to the bottom of the spectrum, a smooth medium, very chiseled treble, sumptuous tonality and the layering becomes holographic, which, for me, is not always very realistic, but you can only think: what a show !

M5s will generally appreciate powerful sources, even if they are not difficult to drive. They reveal the source, the daps’ signatures, so it will be very easy to find the right one if you find the M5 too detailed or too intense. The AK240 for example, more laid back, will go in this direction and will allow to listen to less qualitative recordings without problem.

In my experience, M5 will necessarily require DAPs with very low output impedance, max 1ohm, ideally less will be even better, the E1DA is at 0.5ohm, the QPR1 is at 0.1ohm and works well with it too. For example, forget the R2R 2000 red from Hifiman and its fairly high output impedance. The SP1000 or the N8, will give very good results with the M5 too, thanks to their very low output impedance.



The M5 deliver a solid, corpulent, pure, opulent, full sound flow with an extremely natural and vivid presentation. They excel amazingly with the great classical ensembles as with the most intimate baroque ensemble, jazz, soul or opera voices appearing exquisite and suave, the opulent piano (piano sounds really amazing !), The string instruments as well as the brass shine brightly. Live recording are impressive on the M5 (total immersion). They will love the beautiful contemporary mixes, from West Coast Hip Hop to the swiftest Berlin electro, the fiercest metal or the most catchy pop, all translated with the greatest ease and effort, showing a chameleon skills when necessary.

It’s the marvelous feeling of audio fullness that totally impresses.

In short, the sound turns you upside down from the first notes, and goes crescendo as the music flies, you’ll forget the time. Their flowing temperament, enhanced by a clear, rapid articulation, translating a remarkable tonal precision, a flawless resolution. Even the smallest detail will appear, even on the tracks you know by heart, you’ll hear new details : the breathing of a soloist that the sound engineer had not heard, the fingers of a musician on his instrument, as reliefs embodying music, transcending technique through emotion.

Their maturity captivates without ever showing off, translating the music and artistic intent with completely transparent manner. Without being too intransigent, They will not tolerate bad recordings whereas they will deliver with majesty the best mixes, the character of each source.

Lively, invigorating, vibrant, palpable, this is what translates the impeccable integration of this drivers combination tunned oustandingly !

And the price ? Many may find it too high, but the M5 are more or less at the level of its current competitors, even below some while offering the rare possibility to reshell. I think about the pair which seemed to me the closest to the M5, the Erlkönig, costs more and are only universal. The Vision Ears engineer himself also found that they have in the same spirit, presenting similarities in intensity, spectacular full size sound while keeping each some specificities. I found myself that the M5 have even better separation on some tracks, but most of the time it was hard to find a winner. To me they are the only ones on the very top today, with unparalleled technical abilities. I compare my M5 with SE5ref, Noble K10 or Unique Melody Miracle V1, or even VE8 and they all sound technically outdated beside the M5.

The M5 will of course interest those who are looking for an uncompromising restitution, peaking at the top of what high-end portable audio can currently offer, but also those who are looking for a real mobile solution that could replace a full size headphones and amp rig without sacrificing immersion, presence, intensity !

If you have the money, do not even hesitate !

Kudos Fir Audio !
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100+ Head-Fier
Pros: Sound, design, convenience, build quality and materials
Cons: No (if you leave the price behind the brackets)
Do you know what the secret of a musical piece, which both true connoisseurs and professional critics will call genius? The plays, where the composer, as if a wizard, sends the listener to a wonderful world of trembling consonants and constellations from notes, spend along minor canyons and major peaks, and at the end, during the sound of final, triumphal chords, leaves alone with the flowing euphoria.

However, the magicians from the American company FIR Audio, it seems, know such a magical recipe. Recently, they released a line of in-ear monitors: M2, M3, M4 and M5. I was fortunate enough to be acquainted with the last, five-driver model. If you express your feelings briefly, these are masterpiece CIEM. However, I will talk about this in detail in the review, but for now a few words about FIR Audio.

A year ago, I introduced you to their vacuum cleaners (FIR VAC) designed to care for in-ear monitors. After that, the guys developed some more useful devices for testing CIEM / IEM, as well as very remarkable cables for in-ear monitors.

Well, now we meet - FIR Audio M5!


Text by Alexey Kashirskey aka Hans Barbarossa /


5 drivers (1-ESTAT, 1-BA High, 1BA High-Mid, 1-BA Mid, 1-DD Low)
Impedance: 6, 8 Ohm
Frequency response: 10 Hz – 20 kHz
Replaceable modules: Atom-X
Tubeless Shell design technology
Removable cable "Scorpion Wire": - 1,2м / 1,6м, RCX connectors, jack-3,5мм


Order of custom in-ear monitors

FIR Audio in-ear monitors can be ordered both in universal (IEM) and custom (CIEM) versions. I was lucky to get the second option.


The procedure for ordering individual IEM is quite simple. You need to go to, register, go to the Designer menu, select the model of interest, its design (design, connectors, and cable length) and pay for the purchase. Then you turn to the center of hearing, take your ear-impressions and send them to the manufacturer. After that, look forward to the arrival of your exclusive earphones.


Appearance kit and ergonomics

FIR M5 arrived to me in a silver tin round jar-snuffbox with a screw-off lid. On top is a white sticker with the name of the happy owner of the CIEM and the brand logo in the form of perky protruding rabbit ears.





Inside, this elegant tin can is completely glued with soft foam rubberized material for maximum protection of the CIEM during transport. In addition to the M5, we find a cool cable there, two (black and gold) replaceable atom-X modules, and another, gray module, is already installed in the CIEM, a brush for caring for sound pipes and a leather strap for fixing the wire in a twisted state.




The 26x8 Awg twisted black cable is made of oxygen-free silver-plated copper and has the spectacular name of “Scorpion Wire”. It has twice as many individual cores, compared to standard IEM wires. Due to this, the resistance is reduced by half, which allows the earphones to sound exactly as intended by the manufacturer, without unpleasant impurities and frequency response distortions.

Scorpio is a lightweight, flexible and extremely elastic cable. It has no memory effect and is pleasant tactile. When ordering, I selected new connectors from FIR Audio - RCX and an angled jack of 3.5 mm, similar to Oyaide.




The M5s are large, but fairly lightweight and comfortable. Landing is supposed to be exclusively behind the ear.

When choosing the design of my CIEM, I settled on a black shell and a faceplate with a "Web" pattern. The result was a direct illustration from a Gothic novel: it’s like an old mirror completely covered by a web, on which letters appear: the silver logo “FIR” on the left earphone and the name of the model “M5” on the right. This whole “mystical story” is varnished and polished to perfection.


The shell itself is made flawlessly, it clearly repeats the shape of my auricle and ear canal. The sound guide is neatly covered with a metal mesh, which eliminates the ingress of dust and dirt.

Well, performance, materials, and ease of use - everything is on the highest level here!

However, this part of the review is just an aperitif. If after it your audiophile appetite has played out, now you can go to the main dish.

Sound impressions

Before listening directly, you need to dwell on the technical features of the model. Five drivers are located inside each earphone: one DD dynamic is responsible for low frequencies, one BA for the middle, second BA for the upper middle, and the third BA, together with one electrostatic, are responsible for the correct reproduction of the high-frequency register.

The M5, as well as all other models of in-ear monitors from FIR, is built on the principle of "Tubeless Design". This is the company's patented technology, which means that the design does not use acoustic tubes, as well as separate cameras for drivers. In such solutions, the most accurate calculation is necessary for the correct location of all components inside the earphone shell, otherwise re-reflections and resonances cannot be avoided. Well, when it comes to the use of replaceable modules, the task becomes even more complicated. The way the developers dealt with it in this case definitely deserves applause.


However, let us talk more about this a bit later, but for now, we will deal with replaceable modules. The Atom-X is a metal cylinder valve acting as an acoustic filter for fine-tuning the sound of CIEM. It also pits the air plug that forms between the earpiece and the eardrum. Thus, the pressure exerted on the eardrum is reduced, and our hearing is not exposed to any risks.

The Atom-X modules, as you already know, vary in color: gray - neutral, black adds low frequencies, well, and gold - the most bass.


Listening on the equipment: MyST DAC 1866OCU V.2, Lotoo paw Gold, QLS QA-361, iBasso DX220 (AMP9), iFI xDSD, iFI xCAN, and iFI micro iDSD Black Lable


The M5 played at the highest level with all the devices, the handwriting changed slightly depending on the source, giving the M5 its unique shade. Best of all, the FIR M5 played with my powerful stationary MyST DAC 1866OCU V.2. This, I tell you, is inimitable. Bravo, berry nice, berrysimo! Tasty and lucid! Do not be surprised, I’m chewing blueberries in the course of the play, which is why such berry-juicy puns, ha-ha.


These CIEM can cope with any musical genres without any problems, and replaceable modules allow you to accurately add weighty sound to the sound without touching the rest of the registers. I mainly used gray atom-X, and even in it, it seems to me, bass is quite enough. But I also liked the other two options with even lower elaboration.


By the way, when ordering, you can choose M5 with a built-in gray atom-X. But we must understand that in this case it will not work in any way to finish the bass.

The sound of the M5 is massive, polished and natural, delivered in a neutral-warm manner with a darkened background, a well-designed low-frequency range, well-textured bass, a smooth, extremely rich, detailed midrange and an unusually clear and accurate high-frequency range. This is a thick, adult, thoroughbred and extremely naturalistic way of delivering sound.

M5 give out a sprawling stereo panorama, harmoniously and proportionately building a virtual space both in width and in depth. The volume is amazing, and the dynamic range is wide.

M5 impresses with its temperament, clear articulation, good speed characteristics, high resolution and extraordinary tonal accuracy. I note a competent configuration with excellent driver matching and a complete absence of phase distortion.



The musical canvas is drawn unusually lively, embossed, with a symbiotic plexus of small and large parts of the composition, excellent transmission of contrast. It is integral, volumetric, proportionately built along all axes of sound coordinates.

However, all the above definitions cannot convey the most important thing. Inside the M5 there are clearly not only impeccably tuned drivers, but also a pinch of some magical powder. Otherwise, how else to explain the magical abilities of this model. With these CIEMs, the virtual audio images in my head came to life, grew flesh and became tangible. The virtual world turned into the real one. Now you are reading these lines and smiling incredulously, but in vain, I am not joking. The creators of the FIR M5 not only collected beautiful earphones, but also breathed life into their creation.

Okay, reluctantly set aside my lyrics; let us move on to the frequency amplitude.


The bass is precise, thick and resilient, with good control and quality texture development. It is neatly forced and clearly interacts with the mid-frequency register, complementing it with depth, a rhythmic base and an unusually lively, significant substance. The blow is powerful and biting, going deep down. The drum kit is perfected: powerful rumbles from the dancing of sticks on cymbals and drums scatter on both sides of the listener. Testing of the low-frequency register strikes with accuracy, reverberations and clearly distinguishable impact force. Wow, goosebumps are running down the back!

The mids is smooth, natural, timbrally rich and textured. Here, every musical image is endowed with a bodily basis. This is an extremely naturalistic and melodic manner, with a striking depiction of the contrast and all the details of the composition, where each instrument and every note played is in its place in space. Gracefully stringed instruments, winds and especially vocals. Here there is a light, correct, I would even say, jewelry rise in the mid-to-high junction zone, which adds to the vocal parts a pleasant charm, gloss and expressiveness. This is a well-balanced and at the same time emotional performance, where all elements of the composition are served unusually accurately, large-scale and multifaceted.

High frequencies are reproduced clearly and harmoniously. Their quantity and quality also does not cause the slightest complaints. The register is transmitted cleanly, accurately and distinctly, without sharpness and distortion. This is an unusually reliable and maximally correct manner, with good articulation, served in a light, elegant and comfortable form. Here, as in the other registers, there is agreement and harmonious interaction with the entire frequency range. Everything is beautiful and vibrant, simply amazing!


I cannot resist not to listen to my beloved Paul McCartney in the M5 brilliant So Bad.

Bass smoothly and recklessly fills the space. He waltzes himself and makes the whole composition spin around him. Its pulsation carries away measured drums. Bah, it’s Ringo Star himself following his old friend and paving the way for the rest with his lazy bit.

And here is the sparkling brilliant brute force guitar playing in the strings with windy, light, like a summer breeze, keys.

Paul McCartney's pure falsetto cuts space and time:

And if you leave, my pain will go
But that's no good to me
Girl, I love you, yes, I love you so bad...

Backing vocals scatter on both sides of the listener, going far beyond the boundaries of space and are already fading there.

The singing of violins and cello, enveloping like a languid aroma, makes you tremble with your whole body.

M5 amazingly convey the volume, texture and topography of the song. Every sound, every breath, intonation and touch of the strings are felt by the skin, and at some moment you literally sink in this moving melodic mass.

Amazing, chic, indescribable. It is something fantastic.



As for the frequencies (In the dry)

Lows - timbre-rich, with a powerful clap and a precise rolling kick. The bass is deep, embossed, gives the sound a warm and analogue hue.

Mids - even, smooth, detailed, organic, with excellent resolution. The pitch is clean and layered, with an extremely natural transmission of tones.

Highs - clean, smooth and natural. They are transmitted clearly, accurately and without any flaws.




FIR Audio M5 is an amazing CIEM model that geniuses have created, and I don't exaggerate a bit. For me personally, these in-ear monitor became an opening, a door to the bright future of portable sound. To create such a masterpiece, it is not enough to be a talented engineer; you need to have a deep understanding of the industry, an impeccable taste and a visionary gift. From an excess of feelings, to be honest, it is difficult for me to continue to talk about these earphones. Yes, you already understood everything. Today we were talking not about a good product, but about embodied audiophile's dreams and thoughts.


In addition, if someone says that dreams and thoughts are priceless, then it will be wrong. The price tag in our case is available and it, of course, is also impressive. You can order the M5 model on the official website for $ 2799. Of course, these in-ear monitors are not for everyone, but for the most notorious fans of perfect sound. To them I without the slightest hesitation recommend making every effort, but to purchase these CIEM.



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Headphoneus Supremus
Pros: Top notch coherency
Best treble I've heard on an IEM
Neutral done right
Most generally speaking - everything about it
Cons: FiRCon can be an issue if you have a lot of aftermarket cables
Distribution network in early stages
LID on steroids
I generally have a safe approach to buying audio gear - I mainly go for well known brands and models that have been around for some time, that have been reviewed extensively, with their issues, strengths and weaknesses identified. The first time I took a leap of faith was on FiR as I have been speaking to Bogdan Belonozhko for a while and he's given me a lot of confidence in their brand. Boy am I glad that I did though.


Anyways, a couple of days ago I received the FiR Audio M5, a TOTL tri-brid IEM by Bogdan Belonozhko himself. FiR is a relatively new entrant in the market, and so far they've mostly been known for the Headphone Vac as well as a number of IEM maintenance and diagnostic tools. Well, that's about to change very quickly.

They've been working on a lineup of tubeless IEMs and CIEMs (yes, you read that right - FiR actually makes tubeless customs) - the customs have been around for some time now, but the final version of the universals is now entering the market. They're using a completely new connector, called the FiRCon (or RCX if I'm not mistaken), which promises up to 5000 inserts compared to the current industry standard of about 1000 for MMCX and 2pin. They're also using thicker shells of about 1.1-1.2mm which significantly improves the durability of the customs. Most of these changes are geared towards the pro market, but I'm sure audiophiles would be able to appreciate that as well. FiR also has a lot of confidence in their product and offers a 3 year standard warranty on all their FiRCon products - almost every other company I've come across offers either 1 or 2 years depending on the region you're in.

Enough about the company and onto their flagship - the M5. It uses a DD for the lows, 2 BAs for the mids, and another one BA + an Estat for the highs. A relatively safe choice in terms of driver choice, nothing too unusual or surprising there.


I got an early adopter packaging, so just a box, a cable and the IEMs - I can't say what the final packaging will be like. The cable is an 8 wire SPC, excellent build quality, very flexible and durable, no complaints regarding the microphonics either - generally speaking one of the better stock cables I've received with an IEM - very similar to the 64 Noir upgraded cable if you've seen that one. The IEMs have a black aluminium body, and a rose gold faceplate with the FiR logo on one side, and "M5" on the other. When I saw the IEMs on a photo pre-purchase they seemed a bit too plain for my liking, but in person they look absolutely lovely, and look exceptional once worn - two little jewels. Can't comment on the durability just yet as I have luckily not dropped them, but I doubt there will be issues in that department. The connectors also feel absolutely amazing compared to 2pin and MMCX, with a much more solid insertion, no rotations, no bent pins on the cables or any of that usual trouble. The only trouble is that most aftermarket cable manufacturers don't stock FiRCon just yet but hopefully that'll change soon.

Describing the sound of these is pretty tricky - I listened to them extensively the past 4 days and only today did I find the words to describe it adequately. "Perfectly balanced as all things should be" are the words that came to mind, because of the absolutely exceptional coherency. Too often I see tribrids that emphasise either the lows or the highs (or both), leaving a rather unnecessary V shape, where the mids are heavily recessed. I personally dislike that tuning, and I dislike it even more when you have DD bass and Estat highs which are both extremely dominant, leaving you with these vocals that are barely audible in the background. The other trend that I'm not a huge fan of is co-flagships, or multiple TOTLs - for example the U18t and the Noir from 64 - they feel like they are built to complement each other, and to be able to fully cover my rather large number of genres, I'd need to have both. EDM on the U18t is a big no-go, jazz on the Noir just loses some of that harshness and charm. I'm extremely happy to say that the M5 is 1) largely neutral, and extremely coherent and 2) I feel like it was made to be a single TOTL, able to perform anything you throw at it. At least it sounded spectacular with all of my genres and test tracks.

The lows: the bass in the M5 is an extremely pronounced quality over quantity - just the way I like it. Tuning a dynamic driver is rather risky because you can end up with extremely heavy bass that becomes the only noticeable element of an IEM (CA Polaris II I'm looking at you). FiR have used the dynamic driver for texture, detail and definition of the lows, while keeping the quantity appropriate to the rest of the IEM, without overemphasising it or completely omitting it.

Lower mids: the lower mids are very organic and natural, and I feel like the dynamic driver is helping there too - they have a certain dynamism - male vocals sound really intimate and realistic.

Upper mids: this is one of the strongest points of the M5. Female vocals sound absolutely ****ing exceptional. they are gentle, they are intimate, they take centre stage when they need to and produce an absolutely euphoric experience. They remind me of the Empire EVR, which to this day has the most beautiful female vocals I've heard.

The highs: hands down best highs I've heard in an IEM. They have that Andromeda sparkle, they have the detail and definition on top of that and they can get sharp and almost painful when you really push them. If you are a treble head like me, this will send you straight in a coma. Violins sound like they've come from a completely different dimension - I'd say the upper mids are the best part of this IEM if it wasn't for the absolutely outstanding treble. You can really feel that the estat is working overtime to deliver such an outstanding result. I've also become heavily addicted to the highs of the M5, and find myself missing them in almost every other IEM I listen to.

Soundstage: the M5 places you in the middle of the stage - you can hear the vocals dead in front of you, instruments left, right and behind you. This is quite heavily contrasted to the U18t, which places you in the crowd, a few rows back too. It is most certainly an intimate soundstage - extreme detail in instrument placement, without reaching extremely far out. The soundstage is very important to me and while I would probably prefer for it to be a bit larger to give me that feeling of being a bit further away from the music, I can't say I have been left dissatisfied.

Instrumental separation: Some of the best I've heard, only second to the U18t. Each instrument is an entity of its own, carefully placed and executed.

Detail: This is the part that left me most baffled. I've come to associate tubeless with more smoothness, less detail. 64's Noir for example is the smoothest IEM I've heard, but it's detail retrieval is okay at best. The U18t is extremely harsh and surgical, with insane detail retrieval - try to listen to some pop on it though and just give up 20 seconds in. The M5 is able to pick out the smallest details in a track, and reveal them to you with pure precision.

The best all-rounder I've heard: While many IEMs have a clear preference for certain genres, recordings, sources or cables, the M5 has done an absolutely amazing job at playing anything I've asked it to. Going back to the 64 comparison: the U18t has a clear preference for acoustic instruments, live recordings, loads of detail and huge soundstage - I drool every time I listen to any of my jazz playlists on it. The Noir is pure insanity for EDM, pop or any of the more electronic genres and beats. The M5 comfortably competes with both the U18t and the Noir in the areas where each of them really shines. To say it outperforms them would be an exaggeration, but it is certainly up there, at an extremely comparable level. When it comes to the genres where the U18t and the Noir aren't as strong, the M5 is leaps and bounds ahead in a category of its own.

Sound conclusions: The M5 is heavily neutral, with a touch of smoothness, and exceptional highs - though I wouldn't go as far as calling it bright. Insane detail retrieval and an intimate soundstage take it to an overall level of performance I'm yet to hear from another IEM.
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@csglinux im quite certain yes - at least that’s what Bogdan told me during our conversations
Curious, because it doesn't seem to do anything. Look at the plots I showed in my review. There's a notable shift in FR just going from 0.1 to 1.0 Ohm output impedance. I'll do the math when I get time, but the SPL delta looks to be exactly what you'd expect from its impedance curve.
The math checks out and supports those SPL deltas. But reading between the lines and on the 64 Audio website, I think I can guess what's going on. I'm guessing the M5 does have some kind of "LID" circuitry, and that, without it, its Z (and therefore SPL) variation as a function of f would be even worse.