General Information

The R1 Zenith's bass has been controlled even further along with an elevated midrange and more precision in the upper registers. All these improvements have lifted the R1 Zenith's abilities to another level.

Tuned to perfection using IMR's Gen II custom 13mm Ceramic hybrid driver unit. Utilising a hi-res piezo ceramic driver combined with a beryllium 13mm dynamic driver with uprated neodymium motors for a huge soundstage and precise instrument placement and with a FR from 14-40000Hz to cover the whole audible range of audio.

Fully customisable via the porting system and 5 interchangeable acoustics filters to give you 10 settings for your perfect sound signature. These audio filters allow you to alter bass levels, treble levels and increase midrange as required.


  • Black - Powerful impactful bass, rich mids and controlled highs
  • Pink - Slightly decreased bass from the black filter with the same mids and highs
  • Copper - Maximum bass, lush mids and slightly recessed highs
  • Orange - Balanced bass and mids with rolled off highs
  • Blue - Beautifully balanced across the range, natural and airy sound with perfect mid and sub bass

  • Gen II 13mm driver featuring uprated Neodymium motors with beryllium diaphragm + Piezo Ceramic driver
  • Gen II IMR adjustable porting system
  • 5 Audio filters
  • 2 Pin detachable cable (3.5mm and 2.5mm balanced)
  • Impedance: 32 Ohm
  • Sensitivity: 108 +/- 3DB
  • Frequency response: 14 - 40000Hz
  • 24ct Gold plated 3.5mm Jack
  • 1.4M length OFC cable
  • Hard Case
  • 6.5mm Adapter
  • Huge selection of ear tips for the perfect fit.

Image courtesy: IMR Acoustics
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No DD, no DICE
Pros: Excellent build quality
Exceptionally huge bass
Wide, spacious stage
Good resolution and speed for a dynamic driver
Grunge looks (not for everyone)
Unique in what it does - tuning filters, open/closed
Cons: Package is a bit basic for a $500+ IEM
Cables can be better
Midrange/vocals can be thin, shouty
Treble can be shrill
Poor recordings are savaged
Lacks finesse
Full disclosure: I received an IMR R1 Zenith in exchange for my fair and honest opinion, with no expectation of a favourable review. The views expressed are my own, based on my personal sound preferences and taste in music, which may well vary from your own.


I’ll admit this much: I’d never heard of IMR Acoustics, or its founder and owner Bob James, prior to reading about the R1 Zenith while asking Google to find me wide-soundstage IEMs.

The Zenith is, in fact, a revised and refined version of IMR’s debut effort, the R1. It shares its predecessor’s ability to switch between closed and semi-open modes with a unique rotating backplate, and retains the R1’s swappable screw-in filters that can, quite significantly, change the tone of the IEM itself.

Again, from what I’ve read (I’ve never seen or heard the R1 myself), the original R1 was a rather rough-around-the-edges first attempt that, while impressing with a large and rather odd dynamic driver made of a combination of piezo-ceramic and beryllium, was far from refined.

So what is the Zenith, what does it do differently, and is it worth taking a chance on this intriguing IEM from the one-man show that is IMR Acoustics?


Packaging and first impressions

The R1 Zenith takes the original R1 driver, improves on it, and houses it in a far more polished, well-made aluminum alloy shell that, if nothing else, looks every bit like the $500 product that it is.

Shipped in an understated matte black box that doesn’t exactly scream “luxury”, the Zenith’s packaging is as utilitarian looking as the IEM itself. Inside the box you’ll find a full-length block of dense foam with two small cutouts holding the earpieces. Two more layers of smaller foam blocks hold the eartips (a decent selection of multi-sized silicone, double flange and foam tips are included as standard), and a third block holds the array of swappable metal filters and a 3.5mm to 6.3mm adapter plug.

You also get a small, square carry case inside of which you’ll find two cables, one terminated with a gold-plated 3.5mm single-ended L-shaped plug, the other a 2.5mm L-shaped balanced plug. At this price you should expect to get a balanced cable as part of the package, so it’s good to see one included.


The cables have a rubberised sheathing that feels smooth and not too springy, although they are quite thin compared to the typically braided, teflon-sheathed cables most IEMs ship with today. Both cables are a dark grey colour - which fits in with the overall Zenith aesthetic - and seem to be well made, even though I’m personally not a fan of the two-pin connector (I’ve always found MMCX connectors to be sturdier). At least the connector plugs on the earpieces are both notched and recessed, which should prevent any accidental bending of the pins, and the cable material resists twisting or knotting.

Last but not least, a small calling card explains the differences in sound between the various filters, which I’ll cover in more detail below, and a basic user manual warns you about hearing loss and proper use of IEMs – a nice touch that I don’t often see with other products.

Overall the package in on par for a mid-tier IEM, if somewhat basic and visually understated. The earpieces are well made and beautifully machined, and the mechanism that opens and closes the backplate is fluid and smooth. The filters also look to be made of the same high quality aluminium, and are precisely machined like the earpieces they connect to (if a little sharp to the touch).

Feel and fit

Unless you’re buying a custom IEM, universal IEMs like the Zenith can be hit-or-miss, depending on the shape of your pinnae and ear canal. The Zenith, for me, takes the middle ground in terms of comfort, as in not uncomfortable but not glove-like like either. The tuning filters form the ‘nozzle’ and sit deeper in the ear than I’d like (being fairly wide as well), but not deep enough to really irritate, and any discomfort can be alleviated with the proper tip.

The shape of the housing is small enough to sit comfortably on my ears, although the protruding backplate screw means I can’t lie on my side with them, or wear beanies for that matter. They also look slightly awkward when worn, so expect to get puzzled looks and the occasional chuckle when walking around with Zeniths in your ears.

Since tips – like IEMs – are extremely user-specific, you’ll just have to experiment to find what works best for you. ‘Tip rolling’ with most IEMs is an absolute must, not only to get the best possible fit and seal, but also to change (or preserve) the sound, and the Zenith is no exception. Nothing changes the sound of an IEM more than the tips used, so keep that in mind when you’re reading my sound impressions.

As with most IEMs, I found the Dekoni Bulletz (my own, not included with the Zenith) to be the most comfortable tips with the best seal. My favourite tips, the JVC Spiral Dots, didn’t work as well with the Zenith as they do with other IEMs I’ve owned or tested, either in fit or sound, which is a shame really. The default tips that ship with the Zenith are decent enough, though not the same quality as the two I mentioned above.



Unlike most other IEMs, the R1 Zenith defies a simple description of its sound, but I’ll give it a try: big, bold and brash. Except big, bold and brash only applies to the Zenith with two, maybe three of the tuning filters. The other filters change the tuning completely, and in my opinion, change the very nature of the Zenith (and not always positively).

I don’t normally believe in burn-in for IEMs, but let the Zeniths warm up on some test tarcks for a couple of days before giving them a serious listen. I tried different filter combinations, eventually choosing the black filter not only because it’s the default (and presumably the one Bob used to tune the Zenith), but because I think it brings out the positives of the Zenith’s sound. As such, all the impressions below are based on the black filter, which is described as having “maximum attack with powerful impactful bass, rich mids and controlled highs”.

The other four offer more than mere variations on a theme; some make the Zenith sound like a totally different IEM. For example, the pink filter is supposed to drop the bass a touch without affecting mids or highs (although it does because of the balance shift); the blue filter is said to be “beautifully balanced across the range, natural and airy” (or, in my experience, quite dull and somewhat shrill); the orange filter rolls off the highs, and the less said about the copper filter the better.


As a source I used the 2.5mm balanced cable and a FiiO M11 DAP, which has power to spare to drive the harder-to-drive-than-usual Zenith, and a neutral but musical sound that works well with most IEMs. My songlist included, but wasn’t limited to:

· Crush by Meiko (Playing Favorites)
· Shark Fin Blues by Missy Higgins (Oz)
· Cathedrals by Heidi Talbot (In Love + Light)
· Hello Again by Neil Diamond (The Jazz Singer)
· The Waking Edge by Jethro Tull (Crest of a Knave)
· Viices by Made in Heights (Made in Heights)
· The Saltwater Room by Owl City (Ocean Eyes)
· Doin’ It right by Daft Punk (Random Access Memories)
· Winter 1 by Max Richter (Recomposed by Max Richter)
· Four Minutes by Roger Waters (Radio K.A.O.S)
· The Tide Is Turning by Roger Waters (Radio K.A.O.S)
· Bijou by Queen (Innuendo)
· The Story by Brandi Carlile (The Story)
· My Immortal (Band Version) by Evanescence (My Immortal)
· Love Bites by Def Leppard (Hysteria)
· Hey You by Pink Floyd (The Wall)


The standout spec of the Zenith is its massive 14mm dynamic driver, made from a combination of piezo-ceramic and beryllium metal. This is the first time I’ve seen ceramic drivers in an IEM, since ceramic is notoriously difficult to control and is thus usually limited to higher-end desktop speakers driven by very powerful amps. You could say Bob took a real gamble with this driver, but it’s paid off in at least one aspect: bass.

Not only does the Zenith deliver the biggest, most bombastic bass response I’ve heard in an IEM, it’s even bigger than most headphones, basshead cans included. The bass isn’t just big, it’s also fairly detailed, has decent speed for a large dynamic driver (thanks to the Beryllium diaphragm), and extends lower than a villain’s basement, delivering jaw-shaking rumble when called upon (and sometimes even when not). So big is the bass that when anything tries to get in the way of the lows on a track, it gets squashed.

There’s a part in Heidi Talbot’s soaring hymn ‘Cathedrals’ (0:50) that showcases just how big Zenith’s bass can be. Yes, it overwhelms the mids, almost floods the vocals, but it’s absolutely delicious, especially if you’re a bass addict. Similarly, at the 2:00 mark of Missy Higgins’s ‘Shark Fin Blues’, the sudden rumble takes the song to another level, putting you in a big wide cavern with Missy while the walls and ceiling shake all around you.

The Zenith is made for big bass and bass-driven tracks, and while I’m not a huge EDM fan, fans of ‘the drop’ will never feel short changed here. More nuanced electronica, like almost any track on Daft Punk’s glorious ‘Random Access Memories’, is highly rewarding as well, as is drum and guitar driven rock like Def Leppard.

Playing ‘Love Bites’ off Def Leppard’s ‘Hysteria’, the impact and visceral punch of the drums in the intro is palpable, almost better than I’ve ever heard (or felt) from full-size speakers. I’d go as far as to say these are among the best Def Leppard IEMs I’ve heard, purely for their bass impact, something that can’t be said for some of the better-known IEMs on the market (I’m looking at you, Andromeda).

Pink Floyd fan? If so then you’ll know how easy it is to get the Floyd to sound good, given the impeccable mastering on their albums, but how difficult it is to make them sound great. I wouldn’t say the Zenith aces Floyd, but it renders the drums on The Wall’s ‘Hey You’ so realistically, they’re worth a listen just to hear them on that track.

If there’s bass in your track, the Zenith will brandish it bigger and bolder than you’ve probably heard it before. If it gets too much, you can always switch to the pink filter to turn it down a notch, or open up the backplate to diffuse the sound slightly and widen the stage. If you’re really not much of a bass fan I’d give the blue filter a try, but be warned – all that magic I spoke of above will be gone, and you’ll be left with a poor imitation of what this unique driver is capable of.

On the other hand, if you like what you hear and want more of the same, don’t be tempted by the ‘maximum bass’ copper filter. To my ears it makes the Zenith sound thick and one-toned, with bass overwhelming just about every other frequency. It’s not even a case of ‘too much of a good thing’, it’s just too much.



The Zenith’s midrange is a complete mystery to me. I get that with bass as big and aggressive as it has, something’s got to give. But where I’d normally just say the bass bleeds all over the mids and call it a day, with the Zenith it’s not so simple.

Meiko’s ‘Playing Favorites’ album, released by Chesky Records and recorded in Chesky’s iconic single-microphone binaural style, is a perfect example of what I mean. On the track ‘Crush’ (a brilliant cover of the original, by the way), Meiko’s impressive vocal range doesn’t seem to be altogether there. I know how that sounds, but believe me there’s no other way to describe it. It’s as if part of her lower octaves just aren’t being conveyed (and yes, I did try this with a few different IEMs, and only the Zenith made her sound as ‘odd’ as she does here).

Compounding the ‘problem’ is that the instruments on either side of the room are brought far too forward into the mix, and given the Zenith’s flat soundstage (more on this later), they sound oddly separate from the vocals. This track – and album in general – is possibly an anomaly, especially since it’s recorded differently to many others. But it did highlight for me the fact that the Zenith’s mids are doing something strange.

The Zenith’s mids can be at the same time very fluid and engaging, and at others grainy and slightly jarring. In Neil Diamond’s tear-jerking rendition of ‘Hello Again’, his gravelly voice is almost perfectly rendered, alongside a clear and realistic piano. But switch to Queen’s ‘Bijou’ and the glare in Freddy’s usually pristine voice is too bright to the point of being distracting. I’d call it ‘shouty’ but it’s not shouty in the way that I know shouty can be. The vocals aren’t thrust at you all at once – parts of the vocal are a bit recessed, while others, like the edges of higher notes, are too forward, almost shrill. Recessed and forward vocals in the same track? Better believe it!

When they’re good, the mids, on the whole, are very good. They’re not the last word in resolution, even for dynamic drivers, but they’re not dull and flat either. Pianos and guitars are vivid, if sometimes sharp. Timbre is better than decent, and vocals are generally clear, but can also be thin, especially on poorer recordings. Depending on your music, you’ll either hear the Zenith as euphonic and engaging, or come away from listening sessions slightly fatigued.



I’ve read some reviews calling the Zenith ‘bright’, and I get why, but ‘bright’ isn’t necessarily bad. Maybe it’s just me, but I’ve heard great extended treble before (FiiO’s FH7 and Campfire Audio’s Andromeda are good examples), so I know the difference between good ‘bright’ and blowtorch ‘bright’, and the Zenith can, at times, be the latter. Somewhere along the treble graph there’s a peak or two that will leave your ears waving a white flag.

This is not the treble you want for Mozart or Vivaldi. Listening to Max Richter’s re-imagining of Vivaldi’s ‘Winter 1’, the strings are sharp and shiny, but unnaturally so, with very little texture or decay. The booming bass at 1:28 is expected but stands out in its richness compared to the brittle presentation of the strings. Overall the Zenith lacks the cohesion, subtlety and depth to accurately convey the sonic complexity of this piece, and I’d wager most similar pieces of classical music, at least with the black filter.

However, with the right tips (foamies mainly), the worst of the Zenith’s treble rashness can be mitigated. The orange filter will also roll off some of the highs for you. But the best antidote to crazy treble is not listening to music with crazy treble, or music that’s so poorly recorded you have to wonder why anyone would want to put their name to it. The Zenith will do little to hide the flaws in a track, often magnifying them, so bring on the sibilance if you dare, because you’ll hear it in astonishing detail.

Perhaps I’m being a bit harsh (excuse the pun). The Zenith, especially with the black filter, makes no excuses for being a balls-to-the-wall IEM. Everything it does is unapologetically bold, so it’s probably naïve of me to expect the treble to be any different. Metalheads and those that love guitar-driven hard rock will likely rejoice with all the screeching going on. There’s a lid for every pot, as they say.


The other stuff

I mentioned earlier that I found the Zenith while searching for an IEM with a wide soundstage (being the HD800 addict that I am), and in this regard the Zenith doesn’t disappoint. As a ‘semi’ open IEM it does well in adding air to most tracks, although it still has the typical ‘in-your-head’ sound of most IEMs. Stage width is impressive, with some sound emanating well beyond your ears, but what it has in width it lacks in depth. I’d compare the Zenith’s stage to an oblong pancake – wide at the extremes, but almost paper thin.

Owl City’s ‘The Saltwater Room’ is sweet, melodic electronica pop, with both male and female vocals and range of instruments and effects. It has a wide and lush presentation that, with great headphones, you can almost walk around and explore. Unfortunately, the stage of the Zenith is shallow, and all you have for relief is the above average width. That means many of the effects crowd the middle of the stage and overwhelm the vocals, and are themselves overwhelmed by the instruments that are almost always pushed forward louder than the vocals. This track needs subtlety in its delivery and the Zenith is anything but subtle.

On most tracks imaging is decent, and instrument separation is fair (unless there are too many instruments playing at the same time). On spartan tracks like Made in Heights’s ‘Viices’, instruments and effects lend themselves to the Zenith’s clean and punchy presentation, and the vocals, not crowded by instruments, are distinct and sweet. If this is your type of music, the Zenith has plenty to offer.

Brandi Carlile’s ‘The Story’ is another great example of what the Zenith does very well. Brandi has such a complex, textured voice that it takes great control to render it properly. Zenith almost gets there…and then the drums hit at 0:53 and the guitars at 0:58 and you forget about Brandi and just lose yourself in the melee. That can be good or bad, depending on how you like your alt-country-folksy-rocky music. I’ll give it this, Zenith renders The Story with bags of emotion. It’s all in-your-face and extreme, but your feet will be tapping and your ears will be ringing and you’ll know you’ve been listening to a seriously potent IEM.


Closing thoughts

Breaking the Zenith’s sound into small, digestible descriptions is almost impossible. Give me five songs and five filters, and I’ll give you a dozen different impressions. That means the Zenith is always likely to do something right, some of the time, and I found plenty to enjoy with it while flicking through my music library.

This is a headbanger’s perfect IEM. It looks like something forged on a Mad Max movie set, with rubbery, snake-like cables and muted colouring adding to its steampunk allure. It’s not an IEM I would choose to kick back on the sofa and relax with a glass of wine, but give me a reckless road race and I’ll pop these babies in for maximum adrenaline.

For the asking price the Zenith isn’t cheap, and although the package is decent and the quality of materials and workmanship top-notch, the value really depends on what you want from your IEMs, and what music you’re planning to use them with. I wouldn’t want the Zenith as my only IEM, because even with its array of filters and tip options, there’s no neutral in its gearbox. Even the flattest (blue) filter is not as linear or refined when compared to multi-driver IEMs that have better resolution and finesse.

If you love your bass, and I mean really loveyour bass, the Zenith is well worth the investment, if only to hear what two miniature metal and ceramic drivers are actually capable of. It outdoes my HD800 (easily) and Auteur with the sheer size of its bass, and while the quality is nowhere near that of the desktop headphones, the quantity and control is nothing short of impressive.

It’s a pity the same can’t be said for the mids and treble, which canbe good – excellent in fact – but too often err on the wrong side of strident. However, if you’re not particularly sensitive to glare in your upper mids, and enjoy the occasional grating guitar, this may not be factor.

The Zenith is only the second of IMR’s fledgling lineup, and as such is a very commendable effort in a market generally dominated by safe, inoffensive IEMs. While not perfect, it’s clearly a step up from the debut R1, and has already found a loyal and passionate following among head-fi enthusiasts, and for good reason. It’s better suited to some genres – like trance, EDM, hip-hop, rock – but that’s not to say you won’t find it enjoyable with other genres too. What it lacks in finesse and refinement it certainly makes up in heart.

One thing’s for sure, once you’ve heard a Zenith you’ll know all about it!

Up next for IMR is a fully-open IEM called the R2 Aten, with an even bigger driver and a choice of five bass filters and six treble nozzles. Expect it to be a real sonic medusa, and I wish Bob the best as he continues to swim against the tide in search of his perfect sound. If I’m fortunate enough to get a pair, I’ll be sure to come back here and tell you all about it.
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Dobrescu George

Reviewer: AudiophileHeaven
Pros: + Really good comfort and aesthetic design
+ Package is great for the price, comes with two cables, comes with a large number of tips
+ Customisable sound that varies widely between signatures
+ Smooth, liquid, and warm signature that works well for a lot of music styles
+ Easy to drive from most portables, easy to control and to get the best ouf of them while staying within a reasonable budget
Cons: - The cables are a touch springy
- The signature is not the latest word in detail and resolution, the musicality and smoothness come at the price of the sound not being the most detailed
- The price is a bit high, even if they come with everything you could desire
Liquid Ceramic Flow - IMR R1 Zenith IEMs Review

IMR is a company from UK, who already had a very successful IEM on the market, the IMR R1, but the R1 Zenith now comes to construct on what the original delivered, to offer an even better, more refined experience of IMR's works. With a lot of competitors to stand against, this review will surely be fun, R1 Zenith has to beat bots its predecessor and other IEMs at about 500 GBP / 500 USD.


IMR Acoustics is a growing company from UK, with quite a history of releasing IEMs already, as I have reviewed the original R1 and liked it quite a lot. The new R1 Zenith has even more features to it, and relies on a very unique piece of tech, a ceramic driver, but as a very knowledgeable friend told me before, the higher you go in the high-end speakers, there is always a ceramic driver, seems that ceramic drivers have a magic to them, although they are really hard to master and implement well. IMR stands firmly by their products and will solve your warranty, at this point they are one of the trustworthy companies and you can safely order and purchase from them.

It should be noted that I have absolutely no affiliation with IMR, I am not receiving any incentive for this review or to sweeten things out. This review is not sponsored nor has been paid for by IMR or anyone else. I'd like to thank IMR for providing the sample for this review. This review reflects my personal experience with IMR R1 Zenith. Every opinion expressed is mine and I stand by it, the purpose of this review is to help those interested in IMR R1 Zenith find their next music companion.

About me


First things first, let's get the packaging out of the way:

Now, with the original R1 I wasn't quite that happy with the package, but it looks like IMR changed quite a lot and now their package is not only beautiful but also very all-inclusive.

This time around, the package includes two cables, one single ended and one balanced, both cables are Copper, which means a sweet and musical sound, without hard edges.

There are tips, filters, adapters and everything you could desire, and even a carrying case. It is hard not to give IMR R1 Zenith a golden rate for their package, because, let's be honest, they really included everything, and everything is of a pretty darn good quality.

What to look in when purchasing an upper midrange In-Ear Monitor

Technical Specifications

Build Quality/Aesthetics/Fit/Comfort

Starting with the build quality, you can tell right away that IMR were not joking when they released a new version of their product. While the original R1 looked a bit rough, like it just came out of the machining process, R1 Zenith, the piece of today's review looks like a properly polished product, like what you'd expect from 500 USD, and more.

The design is liquid, it is beautiful, everything is smooth and the shapes of R1 Zenith flows into each other. They are more elegant than they are edgy, but the two screws on the back add a bit of an industrial accent to IMR R1 Zenith

Now, that screw on the back can affect the way the inner sonic chamber acts, IMR R1 Zenith is both a closed, and an open IEM, you can get a more airy, or a more focused sound. Although the soundstage is larger with the sonic chamber open, I tend to prefer it with the sonic chamber closed, better detail, precision and definition.

You can change the sonic filters in the front as well, and you get a multitude of possible sonic performances from IMR R1 Zenith, from a very warm and bassy one, to a more balanced presentation.

On the other hand, the comfort is actually quite good, the large selection of tips works well, and the overall IEM shape is ergonomic and well designed, IMR R1 Zenith sits quite nicely in your ears, you won't be able to sleep while wearing them, but you're surely not going to feel them while using them normally, this is how comfortable they are.

The isolation varies a bit, and so does the leakage because opening the sonic chamber will change how open or closed they are physically, and how much they leak and isolate, but the isolation is on the higher side in most scenarios, you aren't going to be able to hear much from the outside while wearing the IMR R1 Zenith.

If I'd have any negative comment to make, the cables, although there are two of them, and both sound incredibly good, and both are practical, are just a bit springy. The cable is not microphonic, and there are no other issues with it, but it is like a mini cable from Sundara, a bit springy.

The connectors on IMR R1 Zenith are 2-Pin connectors, which are known to be better than MMCX, and overall I feel like IMR R1 Zenith is quite an excellent overall IEM from the build quality, Fit and comfort points of view. Aesthetically, it will be a choice for everyone, but IMR made sure that they left very little space to complain with R1 Zenith.

Sound Quality

As I noted earlier, ceramic drivers are usually found in very expensive products, but are also the hardest to control, hardest to tame, and hardest to sound good. From this point of view, a company is often safer just using BA or Dynamic drivers, as Ceramic drivers, although they hold a magic of their own, they will sound a touch different.

IMR R1 Zenith is like a chameleon. Usually, you'd laugh when thinking that a IEM comes with a number of sonic filters, as usually, the differences between the filters are not that great, but with IMR R1 Zenith, the filters can quickly turn this IEM from one extreme to another, from really smooth, full, lush and bassy, to quite balanced, sparkly and airy.

The port on the back can change the sound from being very airy and wide, albeit a touch vague, to much more precise and detailed, although a bit more intimate. I found that the best equilibrium for me is with the port fully closed, I prefer the better details over the wider and more airy sound with it open.

Each filter provides a very different tuning from the others, and IMR does an excellent job at explaining what every filter does, in a few words, things happen exactly as they describe them. Most of my listening impressions have been done with the black filter, which is the default one, and which seems to be a smoother, more musical one, but which still has quite a bit of sparkle to its treble.

Starting with the bass, you're going to be quite amazed by how liquid and smooth the bass of IMR R1 Zenith is, this kind of bass surely reminds me of a high-end planar magnetic headphone rather than an IEM, you get all the impact, depth and low end reach you could desire, and even if you're a basshead, you're going to have a hard time saying no to this one magical IEM. The resolution of the bass is also outstanding, every single detail being rendered, although the speed of the bass is generally natural, complimenting musicality above ultimate speed.

The midrange, is quite magical, and here the effects of the ceramic driver are starting to be evident. There is a certain smoothness that some people will surely fall in love with. Now that I'm also playing guitar, I think that the best way to describe the sound of IMR R1 Zenith is as liquid as you can imagine, they really compliment smooth guitar solos, rather than being crunchy or having the ultimate resolution. This is actually something to keep in mind, the resolution of IMR R1 Zenith is actually quite good, but they aren't the last word in terms of how much resolving ability they have, instead, focusing on being smooth, musical, lean, liquid and flowing from each musical note to the next. I recommend them with pretty much any musical style, maybe except for large orchestral compositions, where you'd probably prefer having a more resolute and dry sound.

The treble is pretty sweet, although it ends a touch quick, leading to a very smooth, and fatigue-free treble. Despite this, and despite the fact that the texture of the treble is uber smooth, you're still getting a bit of sparkle, making IMR R1 Zenith truly outstanding for long hours of listening, and making them quite ideal when it comes to relaxing and letting your mind experience a truly fluid signature.

I have noted in my video review that I generally would probably not recommend IMR R1 Zenith with metal and rock, because they didn't have enough treble energy, and because they lacked crunch, but this isn't something set in stone, as some people really appreciate a smoother rock and metal experience, so overall besides orchestral music, where I'm quite sure most people are looking for a slightly more analytical signature, IMR R1 Zenith can be described as a very versatile and universal-sounding IEM, especially if you like a more V / U shaped sound, or a W shaped one, depending on the filter that's installed on them.

Portable Usage

When it comes to the portability of IMR R1 Zenith, it is quite excellent, those are IEMs you want to take with you while you're on-the-go, they are easy to drive, they are comfortable, they come with a carrying case, and they isolate well enough from the outside noise to be practical even if you're in a very noisy environment.

Furthermore, they come with two cables, both balanced in 2.5mm and Single Ended in 3.5mm with an adapter to 6.3mm included in the package, meaning that you can connect IMR R1 Zenith to pretty much anything portable, even an iFi iDSD Micro Black Label, if you wanted to.

IMR R1 Zenith is slightly sensitive to hiss, so a smartphone can drive them, but if your smartphone has a bit of hiss, or if your source has it, you may be able to hear it, although, as I always note, hiss is an issue only at very low listening volumes, or if you're not playing music at all, as otherwise, you shouldn't be able to hear the hiss.

Overall, they are very numble, accessible, comfortable and make excellent portable IEMs.


For the comparisons part of this review, I have selected iBasso IT-04, IMR R1 and Acoustune HS 1650CU, all of those being in similar price ranges. Of course, there are many more competitors, but those are the most principal ones, at least at the moment of writing this review, most requests having been for comparisons between these ones. R1 Zenith will also be named R1Z for simplicity during this part of the review.

IMR R1 Zenith vs iBasso IT-04 - The iBasso IT-04 is still quite a magical IEM, but also similar to the Zenith in some ways. Starting with the comfort, both are really comfortable, and both have an ergonomic shape, but R1 Zenith is slightly more comfy than IT04. On the other hand, the cables or rather the cable that comes with IT-04 is better than the one that comes with R1Z, especially in terms of design and how flexible it is. The sound of the two cables should be fairly similar, although I haven't been able to compare them directly, as IT-04 uses an MMCX connector, and R1Z uses a 2-Pin connector. Both IEMs pick hiss similarly. Both IEMs are really easy to drive. Now, the sonic tuning is really different, IT-04 is extremely neutral, bright, much much faster and has a much more detailed bass than R1Z, but R1Z has better impact, a deeper, more natural bass, with more warmth and more rumble. The midrange is fairly similar between the two, although IT-04 has slightly more details, where R1Z is slightly more liquid and more smooth in the midrange. The treble is extremely different, IT-04 has considerably better extension, and more sparkle in the treble, is considerably brighter, and I'm saying this as a compliment, not as an insult, because R1Z feels like the treble ends considerably faster, and is considerably smoother, although if you're looking for a smooth treble, it is clear that R1Z is the choice for you. At the end of the day, if you're looking for extreme depth and warmth, for a really liquid and smooth IEM, R1Z should be your choice, while if you prefer a more neutral, faster, more bright and more extended at the top end sound, IT-04 should be your choice.

IMR R1 Zenith vs IMR R1 - Compared to the original, it is quite evident that the build quality has improved a lot with the new generation. Everything feels better defined, there is more attention to the details, and overall it seems like IMR have redefined their production line when going from the original R1 to the Zenith. The sound is quite similar, although R1Z feels considerably more liquid and smoother overall, and also has a larger bass, and more warmth, where the original R1 feels more balanced and more crunchy, and may have a touch more detail, although it doesn't have the musicality and fluidity of the R1Z.

IMR R1 Zenith vs Acoustune HS 1650CU - Acoustune HS 1650CU is quite the magical IEM, and slightly more expensive than IMR R1Z, but not by a lot, since R1Z's price of 500 GBP is above 630 USD, so almost the price of HS 1650CU new. Now, starting with the build quality, the two actually even look similar, at least a bit, but the comfort is pretty much the same, both are outstandingly comfortable. I never felt the need to take either out of my ears, although the isolation provided by R1Z is slightly higher than the isolation provided by HS 1650 CU. The default cable is better on HS 1650 CU, although the package of both is impressive. When it comes to the overall sound, HS1650CU feels more refined, and has more detail than R1Z, but R1Z has a more smooth and liquid overall sound, a more fluid nature, where HS1650CU has more detail, better extension in the treble, and more emphasis on resolution and detail revealing abilities. Overall, if you're looking for the IEM that has the most liquid, smooth and fluid overall sound, but with a lot of impact, and a really amazing bass, R1Z should be your top choice, while if you love a warm and lush signature, but you'd want it to be more balanced and more crunchy, with more revealing abilities, you should consider the work of Japanese, HS1650CU.

Recommended Pairings

For the recommended pairings part of this review, I have selected FiiO M9, iBasso DX220 + AMP7, and QLS QA361 DAPs. All of those are portables, but I'm getting a strong feeling that this is how most of users are going to be using R1 Zenith. You can check out my video review of R1 Zenith, where I talk a bit about pairings with other desktop DAC/AMPs, like the Mytek Brooklyn DAC+.

IMR R1 Zenith + FiiO M9 - FiiO M9 is always really easy to recommend, it is a DAP that does everything, has a fair price and has FiiO's stellar support behind, so regardless what IEMs you're driving, as long as they're IEMs, you can always consider M9. Now that M11 is almost to me, I think I'll also start recommending that one, but for now M9 makes a really easy pairing with R1 Zenith, with a very transparent and resolute sound, for its price being one of the best there are.

IMR R1 Zenith + iBasso DX220 (AMP7) - DX220 with AMP7 is what happens when you consider getting a real flagship from every point of view, much better dynamics, much better resolution, an incredibly versatile and feature-rich DAP, but with the little thing to keep in mind, that a true flagship bears a flagship price as well. If you're curious what's one of the best sonic performances you can get out of R1Z, you should totally give this pairing a listen and I'm sure you won't regret (although your pockets / wallet may).

IMR R1 Zenith + QLS QA361 - QLS QA361 is what happens when you engineer an extremely potent Player with one of the best sounds ever heard, that's almost perfect from every point of view, but keep things more simple, without Streaming, Android, and without much fluff. In this situation, you're given a DAP with a really beautiful musical sound, that's slightly softer than DX220, but which hides a true beauty within. If there's any issue to keep in mind, QA361 only plays music from a microSD card, so only go for it and its magic if you don't need Streaming services and the such.

Value and Conclusion

This has been one fun review, and I'm sure that if you decide to go with IMR R1 Zenith, you're going to be having quite the fun as well. Priced at 500 GBP, they are on a pretty steep price, but they surely come with everything to justify their price point, including cables, tips, filters, and pretty much everything else.

The build quality is quite outstanding, IMR R1 Zenith is a fully metallic IEM, with its shapes flowing into one another, the bore is angled at just the right angle that it sits naturally in your ear, and everything else has been thought pretty well, in such a way that comfort and design go hand in hand with this one.

The isolation is good enough for your to take them on a walk, and they are easily enough driven from portables that you won't be needing much power, and even a smartphone could drive IMR R1 Zenith, although a better source will surely be giving them a better sound.

Speaking of the sound, the magic of the ceramic sure is there, and the sonic signature changes heavily, depending on what filter you're using and on whether the acoustic chamber is open or closed, making R1 Zenith quite a versatile IEM. With musicality, and a liquid bass placed above the ultimate detail, the musical signature of IMR R1 Zenith is sure to leave you speechless if you're a fan of more fluid and smooth signatures, as even with the brightest combination of filters, they are still quite smooth, in both textures, bass, and in the overall signature.

While for the original IMR R1, the build quality didn't convince me quite as much, the R1 Zenith, as an overall IEM, will be included in Audiophile-Heaven's Hall Of Fame for being a really interesting implementation of the Ceramic Driver, for having a ton of possible customizations, and for being a pretty well made IEM, with a strong warranty offered by the company selling it.

At the end of the day, if you're looking for a high-quality IEM at 500 GBP, that is fully made of metal, which has a truly outstanding design and ergonomic, and which has a smooth, fluid, liquid overall signature, which emphasizes musicality above everything else, then IMR R1 Zenith should be quite high in your list, being one of the best there are at this point on the market, at this price point.

Full Playlist used for this review

While we listened to considerably more songs than those named in this playlist, those are excellent for identifying certain aspects of the sound, like PRaT, Texturization, Detail, Resolution, Dynamics, Impact, and overall tonality. We recommend trying most of the songs from this playlist, especially if you're searching for new most, most of them being rather catchy.

Tidal Playlist

Song List

Bats - Gamma Ray Burst: Second Date

Eskimo Callboy - Frances
Incubus - Summer Romance
Electric Six - Dager! High Voltage
Kishida Cult - High School Of The Dead
Dimmu Borgir - Dimmu Borgir
Breaking Benjamin - I Will Not Bow
Thousand Foot Krutch - The Flame In All Of Us
Gorillaz - Feel Good Inc.
Infected Mushroom - Song Pong
Attack Attack - Kissed A Girl
Doctor P - Bulletproof
Maximum The Hormone - Rock n Roll Chainsaw
Rob Zombie - Werewolf, Baby!
Escape The Fate - Gorgeous Nightmare
SOAD - Chop Suey
Ken Ashcorp - Absolute Territory
Machinae Supremacy - Need For Steve
Ozzy Osbourne - I Don't Wanna Stop
Crow'sclaw - Loudness War
Eminem - Rap God
Stromae - Humain À L'eau
Sonata Arctica - My Selene
Justin Timberlake - Sexy Back
Metallica - Fuel
Veil Of Maya - Unbreakable
Masa Works - Golden Japang
REOL - Luvoratorrrrry
Dope - Addiction
Korn - Word Up!
Papa Roach - ... To be Loved
Fever The Ghost - Source
Fall Out Boy - Immortals
Green Day - Know The Enemy
Mindless Self Indulgence - London Bridge
A static Lullaby - Toxic
Royal Republic - Addictive
Astronautalis - The River, The Woods
We Came As Romans - My Love
Skillet - What I Believe
Man With A Mission - Smells Like Teen Spirit
Yasuda Rei - Mirror
Mojo Juju - Must Be Desire
Falling Up - Falling In Love
Manafest - Retro Love
Rodrigo Y Grabriela - Paris
Zomboy - Lights Out
Muse - Resistance
T.A.T.U & Rammstein - Mosaku
Grey Daze - Anything, Anything
Katy Perry - Who Am I Living For
Maroon 5 - Lucky Strike
Machinae Supremacy - Killer Instinct
Pendulum - Propane Nightmares
Sirenia - Lithium And A Lover
Saving Abel - Addicted
Hollywood Undead - Levitate
The Offspring - Special Delivery
Escape The Fate - Smooth
Samsara Blues Experiment - One With The Universe
Dope - Rebel Yell
Crazy Town - Butterfly
Silverstein - My Heroine

I hope my review is helpful to you!


Contact me!

Great review, and I actually ended up buying one after reading this and I don't regret. These sound phenomenal when amped with the black filters on.

On another note, may I ask what camera/lens combo you use for your review photos? Those look stunning!
Dobrescu George
Dobrescu George
@kmmbd - Thank you, and happy tou like your purchase, and happy I helped with that! I am using a very very budget Canon EOS 200D + either kit 18-55 or 50 f1.8 STM :)
Wow, that's a really nice setup on a budget, and the way you frame the photos - it's really cool. Keep up the good work!

Soham Sengupta

100+ Head-Fier
Pros: Excellent build quality, astounding sound quality, filters makes a drastic difference to the overall sound signature
Cons: Cables included are very generic for such a high-priced pair of IEMs, Gold filter makes the bass very loose and boomy


If you haven’t heard of IMR Acoustics, you can still be forgiven. IMR Acoustics is relatively new to the audiophile market. The company’s owner Bob James or the “Filter Master” as I like to call him was previously employed at Trinity Audio which was quite a well-known brand. After the company went bankrupt, Bob started IMR Acoustics in 2018 and released his first pair of IEMs, i.e., the R1. Those IEMs were highly regarded in the audiophile industry as one of the best IEMs using filters at that time. Then later by the end of 2018, they have released the R1 v1.1 which is the R1 Zenith. It uses a newer version of the driver used in the original R1 and the vent port system (which is used to make its soundstage wider or intimate depending if the port is open or closed respectively) and this is the pair of IEMs that I will be reviewing today.

I’ve had the IMR Acoustics R1 Zenith for just over 2 weeks now and have listened to them for a total time of at least 60 hours and have burned them continuously for 50 hours. I’ve used them mostly daily during this time period to listen to all genres of songs (rock, EDM, pop, movie soundtracks, Western classics, etc.).

Don’t want to read the full review? Here’s your TL;DR :

The IMR Acoustics R1 Zenith is an excellent pair of IEMs that can be used by both bass heads and audio purists alike due to its excellent implementation of the tuning filters and I highly recommend buying these IEMs if you have the dosh to spare for them.

But wait! Before you dive into the review, I have a quick disclaimer for you: I have received the R1 Zenith from IMR Acoustics directly for reviewing purposes. The IEMs are not meant to be returned to them but this doesn’t mean that I have been incentivised or pressurized by IMR Acoustics to write this review for them. All the words used in this review are my own and this review is written in the most unbiased way that I could have done.

Now, on to the unboxing of this IEMs.

Unboxing the IMR R1 Zenith

For a $650 pair of IEMs, they are not cheap and that shows during the unboxing of this product. The unboxing experience rivals that of even much more expensive IEMs than themselves. The R1 Zenith comes in a large book-like case which flips out from the top, exposing the IEMs themselves and a small card which show what the IEMs sound like when different filters are installed.


The box of the IMR Acoustics R1 Zenith
Upon removing the protective foam partition that the R1 Zenith is placed in, we will find a case and 3 stacks of foam partitions and an IMR branded hard carrying case. Underneath the case is a small product quick start guide.


The packaging of the R1 Zenith
Two of the partitions contain 6 pair of eartips including 1 dual-flange eartip, 3 single flange eartips (xl, l, s) and 2 foam eartips. There is already a single flange eartip (m) installed in the IEMs for a total of 7 pair of eartips included inside the box. The third partition contains the filter holder with a total of five filters (4 of them in the holder and the fifth is already preinstalled on the IEMs) and 3.5mm to 6.35mm adapter for amp uses.


Underneath the foam partition of the IEMs
Now, upon opening the case we find there is not one but two cables included inside the box. One is a standard 3.5mm TRS cable for smartphone or DAPs (Digital Audio Players) with single-ended connections. The other one included is a 2.5mm TRRS balanced cable which can be used in DAPs or DAC/Amps with balanced connections.

So, to summarize, when you receive the IMR R1 Zenith you’ll get:

  • The IEMs themselves.
  • 7 pairs of ear tips (3 pairs of large-bore single flange tips, 1 pairs of double flange tips and 2 pairs of foam tips)
  • 2 0.78mm cables (3.5mm and 2.5mm terminations)
  • Hard carrying case
  • 3.5mm to 6.35mm adapter
  • 5 Filters
  • Filter holder

All the accessories that comes with the R1 Zenith
So as far as accessories goes, the R1 Zenith comes with a ton of it and I really doubt that you need anything more for these pair of IEMs (except for probably a set of custom-built cable as the cables included in the box are a bit generic).

Design and Build Quality

Now I will be honest with you. When I initially saw the R1 Zenith, I thought that it was actually a new variant of the Acoustune HS1551Cu because of its venting screw (more on that later) jutting out from the body just like the latter IEM. Anyways, the overall build quality of the IEMs is top-notch. Since it is made of metal (probably aluminium), it feels substantial on the hands but is still lighter than quite a few IEMs I have tried (RHA I am looking at you). The body is made using two separate pieces and then the pieces are screwed together. Also, the R1 Zenith has a 2-pin detachable cable system with gold plated connectors. In the previous model, i.e. the R1, there was an issue where the polarity of the 2-pin connection was reversed which rendered it unusable with other third-party aftermarket cables. But it was finally fixed with this iteration of the R1 Zenith. I have personally tested them and they seemed to work just fine with other 2-pin cables.


The IMR R1 Zenith themselves
Now coming to the cable, IMR Acoustics has used a basic 2-pin connector rubber-coated OFC cable. This cable looks very generic for a $650 pair of IEMs but that doesn’t mean it is bad. The cable is quite thick and feels soft and solid in the hands. Also, the cable is resistant to tangle so that is a plus if you keep your expensive IEMs in your pockets (like me).


The cable used in the IMR R1 Zenith
But overall the cable is perfectly fine and for the price, the overall build quality of both the IEMs and the cables is simply excellent.

Ergonomics and Fit

Now this a place where your mileage may vary a lot. The R1 Zenith like most other IEMs at this price uses an over-the-ear fit. Now my ear canals are small so I used the small tips included in the box. Now, there is something to note here. The cable also doesn’t help with the fit. I have the tendency to listen to my IEMs when I go to sleep, but whenever I lie down, the cable often moves out of my ear and dangles beside it. This is really annoying for me at least and I hope that IMR Acoustics implement some kind of an ear guide in the next iteration of its IEMs. I have also noticed that when using two of the included filters, i.e., the black and the gold filter, they introduce driver flex into these IEMs. This is because there is no venting on the side of those filters to remove the air which is present in the other filters. So that is something to keep in mind. But overall, the fit was fine although it a tad bit on the looser side.

Driver flex is an issue where you will hear a sound like crushing paper whenever you put the IEMs inside your ears.

As far as ergonomics go, even though they are made of metal, they weigh only 6g and thus, it feels really comfortable and light on the ears. I have worn them continuously for 3 hours without feeling the need to remove them from my ears. Sometimes I have literally forgotten that they were in my ears. So, ergonomics is also great in these IEMs and there is honestly nothing to complain about in here.


The fit of the IEMs in my ear is just right, nothing to complain about here
Noise Isolation

Now coming to noise isolation, since the seal was quite good on these IEMs (at least for me), basically most of the ambient noise was cut out. Only the horns of the vehicles and the rumbling of my bus (I usually test noise isolation inside public transportation as it gives a very nice idea of what to expect). So, although it won’t be able to cancel out high frequency and/or loud noises like the metro or an airplane (at low volumes at least), you can expect a decent amount of noise isolation with the R1 Zenith. But enough about this, let’s start with the main factor which is the make-or-break property of any audio gear, i.e., its sound.

Sound Quality

Now, on to the most subjective part of the review: sound quality. Also, I won’t be posting any graphs in this review (or any review for that matter), as I don’t believe in graphs as much as I believe in my ears!

This time, I’ll be listening to the earbuds via 3 sources:

  1. PC -> Fiio Q1 (Mark-1) -> R1 Zenith
  2. Asus Zenfone 5Z -> Fiio Q1 (Mk.1) -> R1 Zenith
  3. Hiby R3 -> R1 Zenith
If you plan on purchasing these headphones or any other high-end headphones for that matter, I suggest you get a good DAC/Amp to go with it. It will go a long way to make your listening experience much better and enjoyable.

I will also list the soundtracks that I’ve used for each section of my sound test. (Note:All my tracks are either 44 kHz / 24-bits – 192 kHz / 24-bit FLAC or DSD64/DSD128.) Also, the filter I have used for this test is the Blue Filter as it is the most balanced out of them all and the port was also set to open. I will also elaborate on each of the other filters provided inside the box below.



Now if you are opting for the blue filter as your daily driver like me, do not expect heart-thumping bass here. If you want that, then I would suggest you to switch to the black or gold filters. Anyways, although the bass is somewhat light in here, it is well textured and very detailed and surprisingly airy. But the sub bass rumble is a bit on the thinner side here. But as I said, the blue filter was not meant for bass and more for a balanced and airy sound signature.

The bass in these IEMs with the blue filter is enough to satisfy most, if not all, audiophiles but those who want more bass just needs to change the filter to a black or gold one.

The separation between the lows and the mids is simply extraordinary. They are really nicely separated from each other. The mid-bass of these IEMs with the blue filter is surprisingly good. It has a nice body and has a bit of impact unlike the sub bass in the track Indica Badu by Logic. And there is a surprising amount of micro detail even in the bass region. Bass guitars have a nice texture and airiness to them and you can literally feel every plucking of the strings on the guitar.

So overall, for a pair of IEMs targeted for audio purist at this price, I would say that the bass response is simply excellent and as I said, changing the filters from blue to black or gold increases the bass dramatically (will elaborate more on this in the Filter section).

Tracks used:
  • Axel Thesleff – “Reincarnation”
  • Martin Garrix – “Animals”
  • Martin Garrix, Tiesto – “The Only Way is Up”
  • Alessia Cara – “Here”
  • Zara Larsson – So Good (album)
  • Jordan Comolli – “Alone”
  • Marshmello – “Alone”
  • Axel Thesleff – “Done”
  • J Balvin, Willy William – “Mi Gente”
  • Logic – Indica Badu (ft. Wiz Khalifa)

The mids is the strongest suit in its versatile armoury. The vocals are more forward than the other frequencies but as the soundstage is wide on these IEMs (more on that later), the vocals tend to sound a bit laid back and relaxed in here. Vocals sound airy, wide and extremely detailed. Male vocals have a really nice warmth in them and female vocals sound energetic and feels really airy without sounding overly tinny. There isn’t a hint of sibilance even in the most sibilant which is a great thing as well. And the separation between the vocals and the other instruments is simply phenomenal. Even in low volumes, it reveals so much detail and clarity in each and every song that I listen to that it really doesn’t surprise me anymore that these IEMs cost $650.

These IEMs bring out an extraordinary amount of micro details in vocal tracks which is simply not present in other cheaper IEMs.

Drums also sound really detailed and clear in these IEMs. In tracks like “Back in Black” or “Thunderstruck” by AC/DC, the drums sounded nicely layered and the separation between them and the vocals were simply astounding with excellent amount of soundstage. It felt as if AC/DC was literally giving you a personal live performance to you for free! In the song “The Reason” by Hoobastank, Doug Robb’s voice (the lead singer of Hoobastank) sounded really airy and the drums had a nice impact, detail and energy to them.

So, IMR R1 Zenith really killed it in the mids department and believe me when I say this, the mids of the R1 Zenith make them worth the asking price of these IEMs.

Tracks used:
  • Adele – 25 (album)
  • Charlie Puth – Nine Track Mind (album)
  • Ed Sheeran – X / Divide (album)
  • Amber Rubarth – Sessions from the 17th Ward (album)
  • AC/DC – Razor’s Edge
  • John Newman – “Love Me Again”
  • Elvis Presley – “Can’t Help Falling in Love with You”
  • Sigrid – “Everybody Knows”
  • Hoobastank – The Reason


Now onto treble. Let’s start with those cymbals and hi-hats. They sound really crisp and energetic with a huge dollop of detail in them. Especially its rendition of guitar is extremely good. They sound clear, well textured and detailed, the guitar takes its time to decay and it decays with a certain smoothness which I really like here and has excellent separation as well from the other instruments in any given soundtrack. In tracks like “Numb” by Linkin Park, even though they are not the best recorded amongst tracks, the R1 Zenith does a splendid job separating the electric guitar from the piano that is played at the part “I’ve become so numb…” which simply cannot be heard properly in other cheap IEMs.

Now coming to pianos, their rendition is simply superb and is quite detailed and have really nice extension in them. In the track “Rhapsody in Blue” by George Gershwin, the piano is handled really delicately and has a lot of detail in it. Church organs in this track never sounded harsh in the R1 Zenith which is really good as I had found it harsh in some other IEMs at exactly the same volume. Now, bells sound controlled and energetic in the R1 Zenith without a hint of boominess in them. Trumpets also sounded clear and natural and is full of detail in here.

So overall, I am really impressed with the treble that the R1 Zenith has offered me.

Tracks used:
  • Led Zeppelin – IV (album)
  • Ed Sheeran – X / Divide (album)
  • Linkin Park – Meteora
  • Amber Rubarth – Sessions from the 17th Ward (album)
  • Pink Floyd – Dark of The Moon (album)
  • John McLaughlin, Al Di Meola, and Paco De Lucía – Friday Night In San Francisco(album)
  • Ludovico Einaudi – Islands: Essential Einaudi (album)
  • Axel Thesleff – “Reincarnation”
  • George Gershwin – “Rhapsody in Blue”
Soundstage, Positioning and Separation

(a) Soundstage and Positioning

Now, there are 2 ways to accurately measure a IEMs’ soundstage and positioning. First, is to use well-recorded binaural tracks (see track list below for more info). The second method (which I personally prefer more) is gaming. I have used two games specifically for this purpose. One is the well-known CS:GO and the other is Hellblade: Senua’s Sacrifice (the latter is a much more immersive experience).

Now, soundstage. For a pair of IEMs, they have a soundstage that rivals even that of my own Sennheiser HD58X which is an open-back pair of headphones. The soundstage in the R1 Zenith is really wide and expansive here and this is all due to the venting system implemented by IMR Acoustics on these IEMs. This venting system is basically a small plate over the driver which can be opened or closed by turning the screw on the back of the IEMs. When the back-plate is open, the soundstage is really wide (just like my HD58X like I said previously and I am not making this up) and when the back-plate is closed, the overall soundstage gets just a bit more intimate, but it is still very wide and I would say that it is about as wide as my Moonbuds Crescent in its closed state which is simply spectacular for a pair of IEMs. But at this price, I simply did not expect anything less than this to be honest.

Now coming to its positioning, I felt that it is really accurate in here. To test it out, I fired up CS:GO and I could easily pinpoint the source of the gunshot. Furthermore, in Hellblade: Senua’s Sacrifice, I could feel the voices whispering in my ears. Even in orchestral soundtracks like in Symphony No.5 by Beethoven, the overall layering and positioning of the instruments is really striking to say the least. So overall, I am pretty impressed with the soundstage and positioning that the R1 Zenith provides, even with respect to its price.

(b) Separation

The separation of the instruments should be, to be honest, one of the highlights of these IEMs. Again, coming back to orchestral music, the separation between the different instruments in, say “Symphony No. 5 in C minor” by Beethoven, is honestly remarkable. You can literally distinguish all the instruments that are being played in the track. Also, the layering of the different instrument in different spaces is also something that I have noticed it doing remarkably well in. So overall, I was really impressed with the separation of instruments it provides.

Tracks used:
  • Amber Rubarth – Sessions from the 17th Ward (album)
  • Yosi Horikawa – Vapor (album)
  • Led Zeppelin – IV (album)
  • John McLaughlin, Al Di Meola, and Paco De Lucía – Friday Night In San Francisco(album)
  • Beethoven – Symphony No.5 (album)

Since this is a very essential part of the functioning of the R1 Zenith, I thought that I would make a separate segment where I would describe each of the Filter’s functions. I will be comparing all the other filters with the blue filter as it was the main filter which I have used here. So, let’s get started!


All the filters included with the R1 Zenith​

(a) Black Filter

First, let’s start with the black filter. Before starting with the song aspect, I would like to say that this filter introduces driver flex in the R1 Zenith as the filter is not vented to produce more bass. Anyways, upon putting on the IEMs with the black filter and playing an EDM, the first thought that came to my mind was that the bass is humongous with these filters! It felt as if there was an 8-9dB increase in the low-end frequency. But the major downfall of this filter is that it makes the bass a bit loose and boomy which will put off most audio purists away from this filter (and the gold filter as well). But even though the bass is increased in such an exponential rate, it really didn’t affect the mids much although it did push it back a little. Male vocal sounds a bit deeper and female vocal gain a bit of warmth as well. Even the soundstage of the IEMs surprisingly was not compromised with the black filter. Treble is also controlled and sounded a bit laid back with the black filter. But I would say that the separation between the instruments suffer a bit. Overall, it sounds really good with EDMs and pop songs in general but I wouldn’t listen to anything else with these filters on.

(b) Pink Filter

Now with the pink filters on these IEMs, there is no issue of driver flex as the filter is properly vented. Anyways, the bass on these filters is quite a bit less than that in the black filter but comparatively more than the blue filter. Its bass is much more controlled than that of the black filter and is as airy as the blue filter. The amount of sub bass is also increased in the pink filter without sounding boomy like the black filter. The vocals sound a bit thicker in the pink filters which I really like about this filter. The instruments sounded a bit relaxed and laid back with this filter. But the sound stage is as wide as the blue filter as well as the separation between the instruments. Audiophiles who are not satisfied with the bass of the blue filter and wants a relaxed presentation will really like this filter. So overall, this filter sounds really good with any kind of music thrown at it.

(c) Gold Filter

Now coming to the gold filter, the driver flex is back again with this filter. The only thing going for this filter is its bass and nothing else to be honest. The bass here is even bigger than the already huge bass of the black filter. Due to this, the mids suffer as the bass often mixes with the low-mid frequencies and thereby reducing detail and clarity, making it sound somewhat congested. Soundstage also takes a hit with this filter as it becomes more intimate. The vocals sound really lush, thick and intimate with this filter and the treble is somewhat rolled off and pushed back than the other frequencies. This filter is for hardcore bass heads who listen to nothing except for EDMs. So overall, this filter is meant only for listening to EDMs and nothing else will sound very good on it.

(c) Orange Filter

Now finally coming to the last filter in this stack, that is the orange filter, there is no driver flex with this filter as well. This filter provides an overall laid-back presentation of the sound. The bass is light with this filter just like the blue filter but the vocals and instruments sound really relaxed and bit distant here. But there is no reduction in detail at all and the soundstage is just as wide as the blue filter. Also, I felt that the instruments tend to roll off with this filter just like the gold filter to really take out the harshness of edgy instruments. This filter goes really well with jazz music. So overall, this filter will be appreciated by people who wants a laid-back presentation of his music without the bass of pink filter.


You should be able to easily drive them out of a smartphone but to really get the full out of this beast, you should definitely get a nice set of DAP or DAC/Amp. They have an impedance rating of 32Ω and a sensitivity of 108 dB +/- 3dB so you shouldn’t face any difficulty while driving them out of your smartphones even though I wouldn’t recommend doing such injustice to a high end TOTL pair of IEMs like this one.

Technical Specifications
  • Brand: IMR Acoustics
  • Model: R1 Zenith
  • Type: In-Ear Monitors
  • Driver: Hybrid Driver (Piezoelectric Ceramic Driver with a Beryllium diaphragm)
  • Impedance: 32 Ω
  • Headphone sensitivity: 108 dB +/- 3dB (1 kHz/1 Vrms)
  • Frequency range: 14–40000 Hz
  • Plug: 3.5 mm/2.5mm
  • Interface: 2-pin (0.78mm)
  • Cable: Two 1m OFC Cable (One balanced and other unbalanced)
  • Weight: 26 g (including cable) / 6g (for each earpiece)

In conclusion, you are getting a well-built pair of IEMs which looks, feels and sounds simply astounding to say the least. It comes with a ton of accessories to get you started and to top it all off, the filter implementation is the best I have seen in all the filter style IEMs that I have tested in my reviewing period. Like such a drastic change in the overall sound signature of a pair of IEMs is rarely seen, even at this price. But the biggest caveat of these IEMs is its price. At $650, you have far left the budget IEMs and have reached the hi-fi category of IEMs where there is a lot of competition and you simply cannot make an impulse buy as it IS quite an amount to pay and invest for a pair of IEMs. But even at that high price, I can say that the IMR R1 Zenith is worth paying for. The sound quality, soundstage and the separation that it delivers is simply remarkable for a pair of IEMs. Plus, not everybody’s sound signature preference is the same. One person might like a balanced sound signature, another person might like a laid-back presentation and another person might like a lot of bass and that is R1 Zenith’s biggest strength. It is suitable for every kind of listener due to its well implemented filter system and I will easily recommend these IEMs to anyone who have the budget of over $500.
Thanks for this great review. I've read many cooments about these sounding metallic and perhaps fatiguing. Would you agree with that. I'm thinking about buying them but that's got me concerned. I'd love to hear your thoughts on that.
Soham Sengupta
Soham Sengupta
Hi, sorry for the late reply. Yeah, so I wouldn't say that they are metallic sounding although you might find them fatiguing with the blue filters. But with the other filters like the pink or the gold filters, you won't notice any of that. Hope it helps. Cheers



New Head-Fier
Hello, can you explain to me the situation with the cables? It's about an inverted 2pin, reverse polarity. I've never seen anything like that. Does this mean that my 2pin cables will not match these headphones? If standard cables do not match what to look for and where.

Soham Sengupta

100+ Head-Fier
Hello, can you explain to me the situation with the cables? It's about an inverted 2pin, reverse polarity. I've never seen anything like that. Does this mean that my 2pin cables will not match these headphones? If standard cables do not match what to look for and where.
the zeniths have fixed the inverted polarity issue of the previous gen. So any standard cable will work with this iem.


Headphoneus Supremus
I've seen a description a couple times now where the treble is described as "metalic" - can someone dive in to help me understand what that means?