RHA CL2 Planar


Headphoneus Supremus
Pros: Remarkable levels of both detail and cohesiveness, price, timbre
Cons: May require some experimentation and effort to get the best out of these (user dependent).

I noticed a page on Head-Fi about an upcoming review tour being run by RHA for their new innovative planar magnetic IEM and was delighted to be offered a place.

My thanks to Colum and the rest of the team at RHA!

From an information page about this IEM:

RHA’s CL2 Planar is built around a revolutionary 10mm planar magnetic driver, usable for the first time in both wired and wireless configurations.

  • Planar magnetic driver
  • Detachable MMCX ceramic housings
  • Supplied with 12-hour Bluetooth® neckband with aptX™ compatibility
  • 3.5mm oxygen-free copper and balanced 2.5mm silver-coated cables
  • Injection moulded ceramic housings
  • Folding carry case, carry pouch, flight adapter and sports clip
  • Supplied with dual density, double flange and Comply™ Foam ear tips
More information: rha-audio.com/cl2-planar

Appearance, packaging and contents:

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The packaging and presentation here is absolutely top-class with a remarkably generous array of included extras.

The IEM came with two cables (as detailed above).

The first is their ‘standard’ cable; a pure copper cable sheathed in clear plastic with a 3.5mm single-ended (SE) plug.

The second is a cable with a 2.5mm balanced plug; I’m assuming from the description that it is silver-plated copper but do check on their website directly or on the threads for confirmation.

They are detachable and use the MMCX connectors and hence can be used with a huge variety of aftermarket cables. In other products I’ve reviewed, the 3.5mm cable is usually the poor, inbred cousin of the premium 2.5mm offering.

However, in this case, I have to say that whilst the 2.5mm is a quality cable, attractive and well made, both sonically and aesthetically, I greatly prefer the 3.5mm copper cable.

Whilst the earhooks are somewhat thicker than I would wish, the rest of the cable is fairly non-microphonic, sturdy without being heavy and looks gorgeous. If cables are your thing.

Aren’t they everybody’s thing? Perhaps that’s just me :p

The MMCX connectors are delightfully easy to attach and detach, without any perceivable looseness.

Ironically, the hardest part of cable swapping was not the MMCX connectors per se, but rather the IEM’s themselves, which are extremely small and with a very smooth polished finish.

Unusually, the CL2 even comes with a Bluetooth neckband, which is a generous addition at any price point. I am a tin-foil hat wearing Luddite, so I eschewed testing it, but I’m nevertheless delighted to see such an inclusion :)

For those of you who like to listen to IEM’s (well, listen to music onyour IEM’s to be precise!) in bed, these are the only IEM’s aside from the now extinct Trinity Audio Hyperions that I have found which fit into the ear without protruding out. I suspect that even ‘side-sleepers’ like myself would be able to use these comfortably, which for me is almost unheard of.

The sound:

I started out using my main DAP to play the music on for testing; the iBasso DX200 (with AMP8 and the new CB12s 4.4 cable).

However, I have a known sensitivity to certain sounds or aspects of treble.

Listening to the CL2 with the silver-plated cable, I found that on some songs I was wincing with too much treble. Switching to smaller, deeper inserting tips and using the copper cable with my DX120, all helped to pretty much eliminate these issues.

A few songs quickly helped me to draw out some of the prime characteristics of this IEM:

Fear – Blue October (Phil Tan Remix)(16/44 FLAC)

Immediate delights are found in the way that the CL2 portrays the pounding drums, but what crept up on me is the way that towards the end of the song, there were quite a lot of things going on (instrumentally speaking) and the CL2 has this marvellous ability to let each of them shine whilst binding them together in a cohesive whole.

The Obvious Child (and The Coast) – Paul Simon(HDTracks 24/96 FLAC)

I listened to The Obvious Child and then listened to ‘The Coast’, another track from the same album immediately afterwards. My impressions are related, so I shall put them both here.

What is highlighted here is just how well the CL2 handles percussion of all kinds. Timbre and decay are absolutely on point and the bassier percussion barks with the authority of a stentorian-voiced drill sergeant telling you to drop and give him 20.

Also, these songs both feature delicate shimmering guitar and other instruments, some more prominent, others only in the background of the mix. However, the CL2 really lets these shine; they seem more prominent and noticeable than with other IEM’s yet without losing any of their delicacy or shimmer (these qualities are magnified further).

When The World Was Young – Jimmy Page & Robert Plant(16/44 FLAC)

This one impresses right from the start. The song begins with (what I believe is) the plucking of a double bass with some delicate percussion layered over the top.

The timbre on both of these are excellent, very realistic and lifelike, and this quality continues as the vocals and electric guitar come in.


Overall, I would describe the CL2 as being an outstanding IEM.

Let’s start with some caveats and the evolution of my impressions.

I am treble sensitive and found these IEM’s to trigger that initially.

I must stress, I am autistic and this is a known sensitivity that I have.

Even with this sensitivity, through playing around with cable, source, ear tips and so forth, I’ve been able to eliminate the issue.

If you know that you are unusually treble sensitive and are happy to try both the included cables (and any others you might have) and various eartips, then I believe you’ll be able to really enjoy these.

If you have such sensitivities and you only want something that works ‘straight out of the box’ with whatever eartips you usually use, then you might want to consider something smoother.

There are probably plenty of people for whom the CL2 will indeed work straight out of the box.

However, I think, more so than on other IEM’s I’ve heard, the CL2 are great rewarders of patience and experimentation. From simple and cheap things like trying different ear tips and playing with EQ (personally I found this wasn’t necessary for me, but some swear by it), to cable swapping and trying different sources or amps.

For me, moving from my DX200 DAP to the DX120, swapping from the included silver-coated cable to the included copper cable and changing from my usual Symbio hybrid tips to the included spherical foam tips actually made a huge difference. The warmer sound signature of the DX120 along with the other changes I made really took the edge off of the CL2 for me, but without compromising the many great aspects of its sound signature.

I would hesitate to describe it as a ‘one size fits all’ IEM, but that’s ok; at the TOTL level, it’s really a question of recognising that certain aspects of a sound signature are mutually exclusive to a certain degree. So, it’s all about finding the sound signature that works for you, and then choosing an IEM accordingly.

With this in mind, here’s the unique flavour that the CL2 brings to the mix:

It has a solid low end that doesn’t bleed into the mids. The signature is fairly linear relative to some of the more V-shaped IEM’s I’ve heard of late. However, there is a lift in the treble that really helps to open up the sound and give a boost to the feeling of spaciousness. There’s no area of the sound signature that I feel is lacking or recessed.

It has a deceptively large soundstage. When I first heard it, I was somewhat underwhelmed with this aspect. But changing tips and extended listening has disabused me of this misconception.

I sometimes noticed sounds that I’ve never heard before in familiar songs (for me, a hallmark of quality in an IEM, especially given that I’ve heard a fair few TOTL ones and have been playing the songs I love on high quality equipment for a good many years now).

I noticed these sounds, and in some cases, I realised I was becoming aware of them because they were presented outside what I had previously thought was the outer limit of the CL2’s soundstage!

A common theme in the songs I tested it with was that the CL2 has really excellent separation, imaging and placement. It repeatedly allowed each individual instrument and vocal in the songs to shine, but without ever compromising the marvellous sense of cohesiveness.

The CL2 has detail in spades, but it is still extremely cohesive. These qualities, combined with its accurate presentation of timbre, make this an IEM that lets you really enjoy the music.


The CL2 is either the first, or one of the first, to bring planar magnetic technology to an IEM in a compact form (and bear in mind that I could say the same thing even if this were the size of a significantly larger IEM; the fact that it manages to implement planar magnetic technology with such expansiveness in such a tiny shell is nothing short of astonishing).

It offers an expansive soundstage and marvellous separation and layering; a high level of detail, accurate representation of timbre and a balanced sound signature with a beautiful cohesiveness.

I think this is a TOTL IEM. If you look at the price tag and conclude that it can’t ‘roll with the big boys’, then you would be making a mistake. Like all TOTL IEM’s what you’re looking for here is whether the sound signature on offer is the right fit for your tastes. If the CL2 sounds like it’s ticking all your boxes, then I encourage you to demo it and thank your lucky stars that they’re not charging £2k or more :)


100+ Head-Fier
Pros: Top value package
Cons: Sometimes challenging tuning
Not the best case in the world
Quick Read Conclusion

RHA have created an amazing “audiophile starter pack” with their CL2 IEMs (the “CL2s”). A stunning set of cables, APTx Bluetooth headset, carry cases and tips galore make the CL2 pack an excellent high-end entry into this hobby. The sound is, in the words of RHA themselves a little “marmite” (meaning you either love it or you hate it). The high mid/low treble spike created, in certain tracks, a sort of metallic/tinny tinge I did not enjoy. So then, a 4 overall – 5 as a package, but a high 3 for the sound signature of the CL2s themselves.

Introductions and General Bumf

This review of CL2s follows a familiar format. As intimated above, I have also gone into a little more detail than usual on the bundled accessories, as they were pretty good!

For the avoidance of doubt, I am in no way affiliated with CTM and have received no inducement from them to write this review.

Test Kit: I have tested the CL2s with a Samsung Note 8 and Galaxy S8 (using both UAPP and Tidal), an 11" Macbook Air (2012 vintage, running Tidal), an Astell and Kern AK70 mk 1 (both balanced and unbalanced), an iFi iDSD Nano Black Label, xDSD and also a Schiit Modi 2 Uber into a Vali 2 ("Schiit Stack").

Preparation: I received the CL2s as review samples and didn't give any additional burn in before any listening as I was reasonably far down the list of reviewers!

Me as a listener: I am not a pro by any stretch of the imagination. I have always enjoyed my music, and my tastes are pretty broad. I go to live music ranging from rock and pop concerts to orchestra and opera. I would not describe myself as having a trained ear, but I am attentive and my ears are in pretty good nick for a 36 year old.

My tastes: neutral to warm, but I do like good punchy bass and I love to hear decent instrument separation. As my experience broadens, my tastes are also extending into extended treble over very heady bass, especially where that treble extension helps to build soundstage, imaging and separation.

Test tracks: Test tracks noted in the review below were the TIDAL 16/44.1 available through their Hi-Fi subscription.

So, on to the main event. [/General Bumf]

Tech Specs

I have set out below the key technical specifications for the CL2s – I presume the quoted specs below are at 1kHz, but will ask RHA to confirm and update accordingly. I also note that, on writing this article, the CL2s are priced at £710 on Amazon.



I was excited to hear the CL2s. The thought of a planar magnetic earphone in a sensible IEM (looking at you Audeze with those spider web IEM monsters!) package is definitely exciting, especially if that planar fast bass was apparent.


You will see from the photos below that the unboxing experience is every bit as premium as the high price tag for the CL2s should demand. The box itself is a sort of “book” style box, made of premium card, and from which unfolds the main box itself. From left to right of the unfolded package are the cables and tips, the CL2s themselves and the Bluetooth headband, then a couple of carry cases (a soft pouch and a much harder magnetic latched case) and the various manuals and charging cable.

Unbosing 1.jpg Unbvoxing 2.jpg Unboxing 3.jpg Unvoxing 4.jpg Unboxing 5.jpg Unboxing 6.jpg


Included in the box with both the CL2s are a 3.5mm terminated cable, 2.5mm terminated (balanced) cable, 2 carry cases, 3.5mm to 6.25mm adaptor, aeroplane adaptor, cleaning tool, silicon and foam tips (small, medium and large of each as well as some proper comply foam tips which are my personal favourite), 2 sets of double flange silicon tips and a warranty card and user guide. Some comments on a few of these are set out below.

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At this price range it is great to see a couple of superb cables included. Microphonics from both are minimal. Both cables are twisted, with the 3.5mm presumably all copper and the 2.5mm looking like a silver plated copper cable. Both cables have some sheathed coiled metal wires like a spring, running back from the MMCX connectors to help retain shape. Both cables have premium, RHA branded terminations and chin sliders, giving a v expensive feel.

Cable 1.jpg Cable 2.jpg Cable 3.jpg


I was really pleased to see such a comprehensive set of tips, included Comply TSX-400 tips. I also found the metal plate that they were packaged felt premium and was a very helpful solution to how to package tips.

Bluetooth NeckBand

This was one of the “wow” items in the package. Whether or not you like the neckband format, including an APTx Bluetooth neckband with the CL2s was, in my opinion, a bit of a masterstroke. The neckband itself is rubberised black, with wires appearing with the bottom, terminating with mmcx connectors. As such, this headband can also be used with any suitably connected headphones/IEMs. The band itself has a USB-c charging input, and a small button set for power and volume.

Sound quality from the neckband was as good as I have heard from any similarly specced wireless DAC/Amps. Sure – this is not a competitor for very focused audiophile offerings like the iFi xDSD (lacking the detail, clarity, soundstage and definition of the xDSD in particular), but even so, SQ was perfectly acceptable especially if you are using IEMs on a journey where you are inevitable going to have a little background noise.

I swapped around between a few different IEMs, auditioning on my CA Polaris and SE425s. I couldn't find any stats for the neckband, but it comfortably pushed both of these IEMs with no interference or evidence of impedance issues.

Headband 1.jpg Cases.jpg headband showing aptx.jpg

Overall Thoughts

As an overall comment though, what RHA have done here, is include in one box literally everything you need to get going with this hobby. Great cables, lots of tips, a high quality Bluetooth headband and a thoroughly decent pair of IEMs is a solid gateway.


Glancing at the numbers above, the impedance figures for the CL2s are fairly low and they do change with different sources. Through a source with a suitably low impedance (like my AK70 mk 1 or iDSD Black Label), the CL2s sung. Plugged into my Lenovo ThinkPad X1 or Samsung phones however, the mid/low treble spike described below was accentuated. Although I don't know the output impedance of my laptop or phones, I suspect the “rule of 8” (headphone impedance should be at least 8x output impedance) is offended with a 15Ω IEM like the CL2.

I also didn't really get on with the harder shelled case included in the box. Personal preference/user error, but I found the cables fell out of it in my bag!

Fit and Tips

Despite cramming a planar magnetic driver in, the shells of the CL2s are actually pretty small – think a slightly bulbous Shure IEM, see pictures below. Consequently, I think these are IEMs that most people will find comfortable. In terms of tips, as mentioned before, RHA have gone all out supplying a full host of tips, including my favourite Comply tips.

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The Sound

Highs, Mids and Lows

With the exception of a spike in the lower treble/upper mid (discussed below), the CL2s deliver an overall balanced and coherent sound. There is detail in the highs – percussive impact in Pearl Jam’s Go, clearly presented above the rapid bass – sometimes an area of confusion or congestion for lesser IEMs but the CL2s showed some of their planar talent here. To really test the bass speed on the CL2s, I threw Thundercat’s UhUh at them. For bass response look no further than this track – the speed with which note after note is pounded out of the bass guitar is often too much, even for otherwise brilliant performers, with a flabby “blurring” of notes demonstrating an inability to keep up with Thundercat’s flamboyance. Not so the CL2s, again demonstrating their talent for rapid response without losing any detail, every note clearly defined.

As indicated before however, there is a spike in the lower treble/upper mid-range, which on certain tracks can create a metallic, artificial quality to the music which I did not always enjoy. I particularly noticed this on acoustic guitar tracks – Oasis’ Married with Children taking on a tinny tinge, which made the otherwise bitter vocals feel a little thin. Move to the orchestral, and the effect was to bring to the fore the higher ranges of the string section particularly. In the right track this actually sounded brilliant – Spring from Vivaldi’s Four Seasons for example. However, in orchestral tracks involving the full breadth of the orchestra (think anything John Williams/Star Warsesque, especially where there should be depth in the brass section) and the effect of this spike is to suppress other sections of the orchestra.

I did not always dislike the CL2s sound signature, which actually brightened up a number of tracks. At times though, it made them a little fatiguing, and the metallic twinge I was hearing on acoustic guitar tracks (a personal favourite) means the CL2s are not at the top of my list for this price range.

On AK70.jpg

Soundstage, Separation and Detail Retrieval

Unquestionably scaling with source, and significantly more detailed through the AK70 than their supplied Bluetooth headband, the CL2s demonstrated able performance across separation and detail retrieval. As mentioned above, I found that the CL2s were able to hold lucid instrument separation together on often challenging tracks where the CA Polaris cannot keep up. Soundstage was also good, with width and depth both on show. Nothing like the size, and lacking the height and holographic nature of a TOTL IEM like the CTM DaVinci X, the CL2s nevertheless convey more space than I have heard from an IEM this physically small.

Brief Comparisons

CA Polaris – a much more neutral tuning than the “V” shaped CA Polaris, the CL2s can’t match the visceral impact of the dynamic driver bass, but outperform on PrAT, especially where the bass is moving quickly.

UE900s – the CL2s outperform the UE900s across the board; delivering more soundstage, greater definition and gleaning more detail form the source materials.

CA FIBAE ME – in a similar story to the comparison with the CA Polaris, the CL2s don't quite have the bass impact of the FIBAE ME but their sense of timing, especially on busier passages, is superior. The FIBAE ME fly away from the CL2s though with detail retrieval, musicality, warmth and instrument texture.

Lineup 1.jpg Lineup 2.jpg Lineup 3.jpg


Other than a small issue with the hard case, and the “marmite” tuning (both discussed above) none!


The CL2s are a lovely little IEM with a stand out sense of rhythm and timing, sold in a superb value package with everything you need to get going with this hobby. To be fair, the tuning of the CL2s, in some ways, make them recommendable. They sound truly different to all other IEMs I have heard and, whilst I did not always enjoy their signature, it makes them a unique point of comparison.
The metallic twinge is because if the SPC Balanced cable.
Pure Copper fixes the tonality issue.
Acoustic guitars are my favorite genre to listen to on the CL2, they sound live and exactly how I hear them in person.
Copper cable is a must.
Nice tip @Kitechaser - they've gone back now, so I haven't had the chance to try this out. Hopefully anybody reading the review will see your comments though.


Headphoneus Supremus
Pros: Easy to EQ
Great Accessories and Build
Comfortable Fit
High quality look
Cons: Lower Treble Peak
Female Vocals sound veiled and compressed
Strings and Cymbals sound unnaturally high

The Scottish outfit, RHA, recently released a fully closed IEM that features a planar magnetic driver in it. While planar magnetic in-ear monitors and earphones are not new, there has never been one that has been made in this smaller form factor and fully closed.

The Audeze iSine series was a large unit that was worn as a hybrid between a clip-on headphone a la Koss KSC series and in-ear canal phones. They sound beautifully with the Cipher cable, Reveal plugin, or the right EQ, but sounded pretty wonky in it’s stock form.

The Unique Melody ME1 was released shortly after the original iSine 10 and 20 were released and featured a more traditional in-ear monitor style but with a large Audeze LCD series look. It was a fully open-back planar IEM like the iSine before it. It comes in both a Universal and Custom IEM option. I have owned the iSine 10 and the ME1 universal, and now own the ME1 custom.

More recently, two Chinese brands have come out with their own planar IEMs, the **** MT100 and the Toneking BL1. They both feature vents in them, and are not truly closed backs are are available for around $200 each. I have yet to hear either one of these.

And finally, the RHA CL2 at $899, was released.

RHA graciously sent out a set of these IEMs around the world as part of the Head-Fi Tour and I happened to miss the boat during the initial sign-up. After contacting RHA towards the end of the tour, they did not hesitate to allow me a chance to audition these, so I am very grateful for this opportunity to demo them and provide you my insights.

Build and Accessories

The RHA CL2 packaging comes packed with accessories, all of the highest quality. The first thing I discovered was the various variety of cables. The CL2 comes with a copper-colored standard 3.5mm cable with preformed hooks, as well as a silver-colored balanced 2.5mm cable with hooks. In addition to this is a neckband cable that converts the CL2 into a Bluetooth device. The Cl2 features mmcx connectors, so users can also use other cables with it as well.

A small selection of tips of various sizes is also included in the packaging, as well and product manual, airplane adaptor, and a usb cable for charging the Bluetooth neckband.

The CL2 features a hard ceramic shell that houses the single planar-magnetic driver. The closed shell has a shiny, glossy piano black finish and feels very solid and lightweight in the hand as well as in the ear. With about an hour of continuous playtime, I do sometimes start to feel a little ear pain on my left ear, but not as much on the right. This was a little surprising given the small size and good fit I was getting on initial placement.

For this review, I will focus mainly on using memory foam tips, but I also had lucky with SpinFit CP145 tipes. The Bluetooth cable and it’s quality are not part of this review, and I will be primarily discussing how it sounds based on 2.5mm balanced connections when available.

First off, the RHA CL2 requires a lot of power. Unlike many IEMs, these have very low sensitivity and require a bit of power output to drive them well. I used the Cl2 in combination with various sources including the Pioneer XDP-300R balanced Digital Audio Player and the Monolith THX-AAA balanced amp/DAC. I also used these with the Cavalli Liquid Spark and on some occasions, the Pete Millet Starving Student Tube Hybrid. Some times the source files came directly from my PC, the XDP-300R or the Hidizs AP80. In all cases, files were either CD-Rip FLACs or streaming through the highest quality Spotify or Tidal Hi-Res or Master quality.

My music selection was vastly varied throughout the time I listened with the CL2. My playlist stretches across most genres and my typical baseline album to listen to is Fleetwood Mac’s Rumours, as this showcases various instruments and 4 unique singers. I also tend to throw in the mix Chris Stapleton, Norah Jones, The Civil Wars, Tegan and Sara, Radiohead, Olafaur Arnalds, Daft Punk, The Roots, Vince Guaraldi, and various other artists and songs when demoing headphones.

First off, the CL2 is one of the fastest headphones I’ve had the pleasure of listening to. It’s not as fast as the Stax SR-009, but it’s faster than any of the planar magnetic headphones I’ve listened to and I own and have listened to quite a few. It’s also faster than the Focal dynamic driver headphones I have (The Elex and Elegia). In general, it makes the iSine 10 and Unique Melody ME1 sound slow with longer decay time. The transient speed is a bit ethereal in this sense.

While the bass response actually shows a little bit of a hump, the speed doesn’t allow the bass to bleed over at all. It’s very tight and controlled, and even sounds a tad lean due to its fast attack. When listening to it side-by-side with the ME1, the bass on the ME1 is weightier and meaner, despite it being rolled-off, but also sounds slower in comparison.

The mids is where the CL2 starts to fall apart a little bit. Male vocals sound natural and wonderful. Again the bass never bothers the mids, and the lean bass and mids are clean and almost analytical in a sense. It does sometimes needs a little more body, especially if you’re used listening to the Audeze LCD series or the HD6X0 from Sennheiser, or even the ME1. In a sense, the iSine 10/20 have this sort of leaner sounding mids, but the CL2 is even leaner. It is a type of sound I do enjoy though, as is the case in the Focal Elex I absolutely love.

The upper mids is where things start to get a little, well, weird. This is due to an abnormal rise in the upper mids that peaks up around 4KHz in the lower treble and then steeply drops down to 6KHz. Normally, I do enjoy a little bit or presence here, but the CL2 rises over 5-7dB more than I am used to in this region, and it’s an area, again, that I like boosted (see Hifiman HE560, Focal Elex, Tin Audio T2, KZ ZSN, etc as examples of headphones I gave good scores to and share a peak here).

This giant peak does a few things. First, it completely exaggerates string instruments and brings them front and center. It also makes cymbals splash more. In both cases, these sound unnaturally high and harsh. I love hearing the intricacies of guitar work, and that peak does help you hear every last detail, but it makes the timbre off and sound very unnatural. In addition, this peak makes the upper-mids and especially female vocals, sound veiled and compressed and, again, unnatural. I never enjoyed Norah Jones or Stevie Nicks, and Liz Fraser’s crazy voice sounds even crazier.

The rest of the upper treble range is also boosted, but does not suffer as badly with large peaks, though is still a tad uneven. The fast planar speed really helps level off this area though and gives it an electrostatic-type sound to it. Very fast and slightly artificial.


In comparison, the ME1 is quite dark sounding. The ME1 is a shade darker than Diffuse Field neutral, but in general hovers very closely to that sound profile, while can be at fault for a small bump around 1KHz which creates a tad of shouty sound. The CIEM version I have cleans that area up a little bit and it’s less bothersome, while generally evening out the upper mids and treble.

I found that while the ME1 has some unevenness in sound and is darker and richer than my typical preference, that is was much more coherent than the CL2, and that was really due to that large peak in the lower treble.

Luckily with a little bit of equalizer work, and bumping that region down 5dB or more, the CL2 starts to sound more normal, and helps fix some of its biggest flaws. Similarly, the ME1 can be fixed with some smaller adjustments in the raising the treble region a couple dB and raising the subbass up. The iSine can be fixed using the Cipher cable, Reveal Plugin, or some small tweaks using EQ.

What am I getting at? It seems every planar magnetic IEM has some flaws right now, but they benefit from very low distortion numbers and ability to eq to your needs. I think the Cl2 requires the most EQ work to correct it’s flaw, and I find it’s offering price a little high. The overall package is quite handsome and attractive with the nice cables and Bluetooth kit provided though.


1000+ Head-Fier
Pros: Very smooth sound, sound incredible with classical and brass instruments, extremely comfortable, well made, abundance of different size/style tips, unbalanced copper cable AND balanced silver cable AND wireless neckband all included,
Cons: Bass light, not sutible for all genres of music,

An awesome technology that, at least to me, has infinite potential is the planar magnetic genre. Before now, I’ve only experienced them in full sized headphones and have always been interested in hearing them in other applications, namely the iem. Thanks to RHA, my time has come with their RHA CL2 planar magnetic iem. Coming off the high praise and recommendations of their ever popular T10 and T20 models, to say I was overjoyed to try out their top end model would be an understatement. So how did my first experience with not only a RHA product but also my first planar magnetic iem go? Allow me to share my experience will you.

A little about me

I would like to say that first and foremost I am NOT an “audiophile” but rather an audio enthusiast. I listen to music to enjoy it. Do I prefer a lossless source? Yes, of course. But I can still be very happy streaming from Pandora or even my YouTube “My Mix” playlist. I also prefer equipment that sounds the best to me personally regardless of what frequency response it has or rather or not it's “sonically accurate” and I always have and shall continue to encourage others to do the same.

I'm a firefighter for both the civilian and military sector and the cliché of wanting to do this since I was born couldn't be more present with me. I've worked hard over the last several years to earn this position and now it's time for me to work even harder to keep it.

My interests/hobbies are powerlifting, fishing and relaxing to audio products and reviewing them to help other decide on what products would work for them. Few things make me as an audio enthusiast/review feel more accomplished than when someone tells me that I helped them find the type of sound they've always been looking for.

Now, the sound signature I personally favor is a relaxing, warm and sensual sound that just drifts me away in the emotional experience of the music being performed. Yes, accuracy is still important but I will happily sacrifice some of that if I'm presented with a clean, warm sound that can wisp me away into an experience that makes me yearn for more.

My ideal signature are that of respectably forward mids and upper bass range with the bass being controlled but with some slight decay. I like my treble to have nice extension and detail reveal with a smooth roll off up top as to not become harsh in the least. Examples of products that have given me chills and keep giving me the yearning for more feels are the (in no particular order) Bowers & Wilkins P7, Oppo PM-1/2, Empire Ears Hermes VI & Zeus XIV, Audeze LCD-XC, Meze Headphones 99 Classics.

Equipment used at least some point during the review


-LG V20/HP Pavilion

-Playing Pandora, YouTube, and various format personal music


I am by no means sponsored by this company or any of its affiliates. They were kind enough to send me a product for an arranged amount of time in exchange for my honest opinion. I am making no monetary compensation for this review.

The following is my take on the product being reviewed. It is to be taken “with a grain of salt” per say and as I always tell people, it is YOUR opinion that matters. So regardless of my take or view on said product, I highly recommend you listen to it yourself and gauge your own opinion.

The Opening Experience



Why I feel so strongly about the initial unboxing experience

Please allow me to explain why I feel so strongly about the initial unboxing experience with a product. Maybe it’s due to my southern roots in the hills of eastern Kentucky, but I’ve always been raised under the pretense of when you introduce yourself to someone for the first time you present yourself with confidence, class, character, pride, and competence. You greet the other person with a true warm smile, eye contact and a firm handshake. Anything less or short implies to other person that you either don’t care about them, are too full of yourself, too busy to be bothered by the likes of them, or worse, just generally disrespectful.

As a consumer, I take this same belief to when I open a new product. Why? Because think about it this way. How else can a company introduce themselves to their customers? How do they present their products? Are they packaged with pride and presented in such a way that makes the listener eager to listen to them? Or maybe they’re just wrapped up and placed in an available space. How about the box itself? Is it bogged down with jargon that says look at this, look what I can do. I’m better than anything on the market and here’s why read this and check out that. Or, is the package clean, simplistic and classy? As if saying to the customer ‘Good day, pleasure to meet your acquaintance. Please give me a listen and allow me to show you what I can do and allow my actions to speak louder than my words.’

This is why I feel so strongly about the initial presentation of a product, and I feel it’s truly a shame more people don’t. But with all that aside, let’s discuss how this products introduced itself shall we?

The outer box is that of a nice cardboard material that I thing is almost exactly what I love seeing. The front has an enlarged picture of the CL2 iem, their branding, and special wired/wireless feature it has. Nice and simple, exactly what I love seeing. As you rotate the box you’ve a side with a couple features but nothing to deter away from its simplified appearance, until you get to the back of the box. The back has a picture of the wireless neckband, the cables, the connectors, and a lot of “look at me’s (repeated in multiple languages) that I personally believe doesn’t need to be present on a product of this price range. The CL2, if given the chance, WILL prove its own merit. I know I’m foreshadowing the rest of this review a little but it doesn’t need to gloat about what it can do, all RHA needs to do is let the CL2 speak for itself and I’m quite confident people will understand what they’ve just been received.

As you open the package you’re back on track with a premium product being showcased as such. The interior box is a tri-open box that on the left most tab holds your silver coated 2.5mm balanced cable (which I was unable to test during this review [couldn’t find my DAP that has balanced capabilities]), the copper unbalanced 3.5mm cable and lastly and absolutely incredible assortment of different tip sizes and styles that I strongly doubt someone won’t find their perfect tip with (unless maybe you’ve SUPER small ear canals). The center tab is where your magic is. You’ve the front and centered RHA CL2 iem placed in their cutout foam casing and surrounded by the wireless neckband. On the right is where you’ll find the warranty and instruction manual (on the outer sleeve), the TYPE C charging cable (THANK YOU RHA for implementing this for your flagship product, I hope other companies follow your lead), airplane adaptor and two carrying cases. The two cases provided are a soft pouch meant to carry the iems (in whichever mode [wired/wireless] you have equipped) and perhaps the charger or so while the hard case is able to carry just about everything (but it is a bit larger). And then lastly, a list of everything included in the container.

I must give RHA well earned applause. They did a fantastic job with their flagship product and though I felt like I was originally going to get a “handshake” from someone who’s trying way to hard, they turned out to deliver a very nice and memorable “handshake” that was both firm and full of confidence and competency.



Continuing down the line of solid impressions is the RHA CL2 build quality. The CL2’s frame is made from beautiful ceramic (injection molded) that gives is a truly premium feel and weight that’s very respective of its $900 price tag. RHA decided to go with the concha style with the CL2 and personally, I’m very happy they did, but I’ll talk about why in the comfort section next. The horn is that of the most common size so finding aftermarket tips should be very easy, however with the outstanding selection that RHA provides I strongly doubt you’ll need to. Lastly, RHA engraves each iem with their logo on the outside and the product name and ear location on the inside of the ceramic frame.

The cables are DETACHABLE. To one up something that I already love seeing, the cables that RHA provides are built very well and feel truly premium. I honestly can’t tell you how many product, some costing multiples more than the $900 asking price, that simply provide an “it’ll do” cable but no, RHA provides not one but TWO high quality cables, one copper cable (terminated in traditional 3.5mm) and one silver coated (terminated in balanced 2.5mm [which I was unfortunately unable to test due to me being unable to find my only DAP with a balanced port]).

From top to bottom RHA has constructed their flagship CL2 iem expertly and with competence that is not to be overlooked. I for one can only speak from my point of view but when I hold the CL2 in my hands I can feel a lot of pride that was placed in the creation of this iem and give RHA their due respect because a product of this price tag should be representing as so and RHA most certainly provided this.

The wireless neckband it about as simple as you can get for a neckband. It’s made of soft, flexible rubber with all the controls on the right side (signified by the red dot and “R” on the MMCX connector tip). To be more precise about the right side you’ve the power button on the thicker part in which you simply hold down the button to turn it on and continue to hold to put it into pairing mode (about 5 seconds total). On the cable itself is where you’ll find the microphone and volume/track control module.



As mentioned above RHA decided to construct the CL2 in the concha style casing which I am VERY glad they did. I’ve tried a many of different types and styles of audio product means to go in ones ears and none have ever been as comfortable to wear for long duration and in various positions as the concha style has. I have worn these for several hours on end on multiple occasions and not once have I ever felt the need to readjust them let alone take them out, I’ve literally slept in them on my side. Now, I do have larger than normal ears so that may play some factor but the CL2’s are flush in my ears and, though holding in your hand they have a premium weight to them, they practically disappear. I honestly can’t think of a single complaint towards the comfort of the CL2’s, RHA did a fantastic job.



Before I start this section. It should go without saying but though I link YouTube videos when I’m giving examples, this is for convenience only. If applicable, I HIGHLY encourage you to listen to the music I’m referencing on as high a quality as possible to experience the fullest sound possible.

A key difference between this iem and others is that, well yes it’s a planar magnetic instead of a traditional BA or dynamic, but it also comes with its own wireless neckband. Originally I thought that it was simply a means of making the Cl2 wireless but after listening to the CL2 back and forth from wired to wireless I immediately discovered that the sound becomes quite different from a wired and wireless experience. Though yes I’ll talk about it more individually, the overall difference that I’ve noted is that when going from wired to wireless the soundstage becomes notably smaller and the biggest change is the increase in bass response. So from here forth my standard reference for my review will be using the supplied copper cable (so a wired connection). If I believe there’s a notable difference when switching to a wireless connection, like I did above, I will point it out within the same section.

The overall sound of the RHA CL2 is definitely a brighter and analytical one. The first thing I noticed when listening to them is the focused upon treble which does shift the spectrum towards that end of the spectrum. Soundstage isn’t the largest, and gets even smaller when using it wireless, but it most certainly has an impressive level of imaging, separation and the ability to locate individual pieces in an ensemble. So with this being said, when listening to classical music, especially horn instrument, my goodness did the CL2 shine brighter (in the good sense of the phrase) than about any other product that comes to mind. But so I don’t mx up my sections, please allow me to further elaborate of the RHA CL2’s individual musical characteristics so that I, hopefully, can better describe them.


As I touched on in the above main section, the CL2 performs so darned beautiful with horned instruments. When listening to them, and even writing this review, an anime I loved, Sound Euphonium, immediately came back to me as being a perfect showcase for what I’m talking about. Most specifically their (I believe, it’s been a while since I watched it) final performance of “Crescent Moon Dance (also a “better” non anime version here).” Each horn sounds so lifelike and real that it’s quite difficult to not believe I’m at the performance when I’m closing my eyes and allowing the music to overtake me. Sadly, when using the wireless format, though it’s still wonderful, it doesn’t have that same magic as they’ve toned down the treble to increase the bass.

Though, in my personal opinion, these show their true merit with horn instruments, classical as a whole really sounds fantastic on these. Take “Spring Waltz” by Chopin shear or “He’s a Pirate” by the Auckland Symphony Orchestra. For an iem the level of detail retrieval and separation and depth are terrific. To add to this, though yes, he CL2 is, IMO, quite treble biased, not once did it ever become piercing or unpleasant to listen to. The roll off up top is soft enough that, unless you’re very treble sensitive, I don’t believe you’ll have any issues with these.

On a personal, subjective note before moving on, I really can’t speak higher about these in terms of classical music and especially horn music enjoyment. RHA did a truly beautiful job.


Coming from what I hope was a well showcased love of the treble abilities of the CL2 I admittedly had strong doubts that it would be near as good coming down the frequency band. Oh how I was wrong. My goodness does the CL2 have some magical mids, especially if the artist you’re listening to had a mid to mid high tonality. Of all the songs/artists I’ve listened to during my time with these none have resonated more magically than Michael Buble and more specifically his song “Feeling good.” Not only does it REALLY show how good Mr. Buble sounds but you also get those luscious horns to experience as well. If you can only listen to ONE song through the CL2 to experience it PLEASE let it be that one (and wired if I can also encourage). But continuing onwards, and a note as well. IMO the CL2 showcases its midrange and vocal capabilities much better through a wired connection. The reduced soundstage and bass increase, IMO, though still sound fantastic, just doesn’t do what the CL2 overall specializes in and does very well through its supplied copper cable.

To me, the mids are where the soul of the music are. This is where the vocals and emotion of the artist really reach out to the listener. When listening through the CL2, though some artists tonality is SLIGHTLY shifted higher, you really can feel just what the artist is portraying. “I lived” by One Republic (cover by Anthem Lights) is a wonderful example of this. A very good feeling song and though the AMV linked kinda steers you into an experience as well the song itself and artist singing is a great experience and the CL2 plays is so clean and real sounding that it’s almost like I was the one being sung to.

I know I stated above that the artists overall tonality is slightly shifted higher due to the bass bias but I really have nothing bad to say about the vocal representation of the CL2. They’re so beautiful to experience. Even if the song has some deep throated parts like what’s in “Muddy Water” by LP or like all of “Arlington” by Trace Adkins, though, to me personally, they sound better on a warmer product the CL2 is no slouch and portrays great body in its presentation and I for one have no complaints.


My trusty ole “Blah Blah Blah” by Arwin van Buuren, or “Oracle” by Timmy Trumpet if you want a deeper sub bass hit; despite being a treble focused iem this song has been a great bass test song for me (that’s also quite fun to listen to) and proves that the planars inside the CL2 can give you those rumblies you like (to a degree [and really only via wireless mode]). As my personal tastes prefer a more warmer sound (mid focused with a small bass nudge) the CL2’s, for me personally, never really satisfied my tastes for overall musical enjoyment. The classical genre, as I’m sure I’ve proven by now, is a fantastic experience through the CL2’s however my other favorite genre of hard rock/metal never got the same love.

Planars are known for their speed and control with bass and the CL2 is NO slouch to this belief. The attack and minimal decay competes with any other planar I’ve heard regardless of price however perhaps due to tuning or even its size limitations there not a very full sound. If you are by chance familiar with the Oppo PM-3 headphone, there’s remind me very closely of that overall sound. Quick, controlled, but bass light (though if played through wireless mode the bass is increased a respectable degree but not enough to change its overall sound).



To conclude my thoughts and review of the RHA flagship CL2 wired/wireless iem, I am honestly blown away by them. Though overall their sound isn’t to my personal tastes as a whole that is only meant as a personal input. Objectively speaking this product is something I give my wholest and fullest recommendations to if you’re a lover of classical and vocal focused music. These shine brighter that MANY other product, some costing several times these, and should strongly be considered if you mainly listen to the genres said above. RHA really did a wonderful job. I will sincerely miss these.

Also, make sure to check out my unboxing and review videos. They’re pretty awesome AND you getta put a face to the Army-Firedawg name. If this review helped you out at all please hit that thumbs up button for it really helps me out a lot. Till next time my friends, stay safe.


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Great review mate, good job!
@volly thank you for the compliment my friend, I appreciate it.


New Head-Fier
Pros: Transparency
Cons: Edgy treble
Artificial timbre
Design shortcomings

I'm going to use this section to do what I normally don't: discuss a product's packaging. The CL2 comes in a box that at first appears of moderate size but unfolds to reveal quite the accessory package: a plentiful tip selection; two cables—one copper and terminated with a 3.5mm unbalanced plug, the other silver and terminated with a 2.5mm balanced plug; a Bluetooth neckband; a USB-C cable for the neckband that I suspect will mostly be cannibalized for use with smartphones; and a neat soft zipper pouch, which feels adequate given that the CL2 is metal. Clearly a lot of work was invested in developing the unboxing experience. It's a fun little adventure, but, as always, once it's over, you're left with some over-designed cardboard.

Oh right, and a pair of earphones.


Note: All listening analyzed below was done with the iBasso DX200 w/ Amp 1 and RHA's included copper cable unless otherwise stated. Unfortunately, I didn't have access to any of my other DAPs during my review period; as for the cable, I compare the included silver one in the review, and I don't have any experience with Bluetooth audio so I left the included Bluetooth set alone.

A (mostly) well-executed but fairly standard "reference" approach, the CL2 Planar defaults to a razor-flat frequency response all the way up and down the spectrum—neutral is the keyword here, not natural. However, the CL2's dynamic range and transparency are excellent, which means its signature is determined less by RHA's engineers and more by those mastering your music. Whether or not you want to be at their mercy is up to you…but regardless, there are limits to the CL2's plasticity, and ultimately it will never sound like anything other than a stoic studio monitor—though it does a better job than most.

Bass: The CL2's bass response is easily the most controlled presentation I've ever heard. Unlike many sophisticated bass tunings that manage not to dominate too much despite being ever-present, the CL2's bass is actually capable of anything between completely stepping out of the way and properly taking charge of the signature. Impact is a tad to the light side no matter what, but sub-bass and mid-bass are dead even with each other, so it doesn't feel deficient (excepting EDM, hip-hop, etc.). No, it won't match proper basshead monitors for sheer volume, and it doesn't have the delicious texture or decay of a dynamic, but it blends speed, presence, transparency, and timbre into a perfect bass smoothie for people like me who want to have it both ways: to dance to The Knife, rock out with Queen, and appreciate Chris Isaak's more tender vocal performances, all without switching gear.

The CL2's bass is crazy fast: even recordings whose congested, nimble basslines flummox every other monitor I've heard, the CL2 handles without a sweat: the limiting factor becomes your own ability to process everything similarly quickly. Timbre is also a strong point: different instruments sound different, and, more importantly, sound like they should. Organs sound like organs, string basses like string basses, synths like synths. That said, each sounds like itself: the CL2's bass doesn't quite have the necessary analogue richness to convince you that you're listening to a real instrument. Your brain is fooled, but not your ears—or maybe it's the other way around—the point being that the CL2's bass is expertly poised, but, like an arrogant student, it knows it a bit too well. It will faithfully turn 1s and 0s exactly into their corresponding soundwaves, but it's unwilling to fudge the numbers, and consequently it can't bring you into the music as well as many smoother, more relaxed monitors.

Mids: While the CL2's bass is subtly impressive, its mids are merely unoffensive. They slot into the presentation nicely enough, just without any tricks up their sleeves. While this isn't necessarily a bad thing, it doesn't give me much to write about. Mids are pretty much level with the bass and treble on average, or perhaps the tiniest bit forward, but the CL2's shapeshifter bass means the mids, possessed of lesser dynamic range, don't hold any consistent place in the signature. Timbre is still good, but not as realistic as in the bass, and there isn't much in the way of body no matter what—even when the mids are brought forward in the mix, they don't bring with them a commensurate increase in richness, which leaves both vocals and instruments feeling thin.

Detail in the mids is as good as anywhere else, which is to say excellent; though, again, this doesn't translate to accurate texture. You can hear a finger slip on a guitar string, but it doesn't translate to the illusion of a human guitarist. It's a strange disconnect, but as far as monitoring goes, I figure such a quirk is acceptable.

Treble: And here we get to the problems. The CL2's treble response is pretty much in line with everything else, but it has a peculiar edginess to it that I've never experience elsewhere. Coming from the decidedly warm and smooth Empire Ears Phantom as my daily driver, I fully expected it would take some time for me to adjust to a more forward treble like was necessary with their Zeus and ESR, but I never did adjust. The CL2's treble isn't just bright or forward—in fact I don't think either term describes it well—but it's somehow stabby and piercing. Flutes, trumpets, synths, percussion, everything sounds like its trying to split your head open. Listening at lower volumes tames this, but doesn't completely vanquish it.

Even with the painful aspect ignored, the treble's timbre is less than stellar, and that really confines it to being a studio monitor, where otherwise it might have also been a good choice for classical music. Trumpets in particular just don't sound real, triangles strike your eardrums with a vengeance, etc., etc.

Mind, all this is already with the warmer copper cable. The silver cable trades away an ounce of timbre for one of clarity, and an ounce of bass for one of treble. In my opinion, both bad trades that mostly exacerbate the above treble woes.

Resolution: As can be expected from a planar driver, resolution is among the best. Macro and micro details are superb, on display without distracting from the music or accompanying a peaky treble. Clarity is second to none: there's simply nothing that will make the CL2 sound veiled and no cacophony it can't sort out. Transients are blisteringly fast, although sometimes a bit too much for their own good: there were instances in my listening where micro details I know well nearly passed me by because they were there and gone so quickly.

Soundstage: The CL2's soundstage isn't expansive, but it's well-proportioned, and the use of the space is very efficient. Instruments are kept small enough that even without an enormous stage to put them in, the CL2 just doesn't run out of space or individually identifiable positions to put things in. Imaging is therefore solid, though it suffers a little due to the artificial timbre: it's easy to place where things are on the stage at any given moment, but those things are never convincingly human.


At first, things appear just fine. The earphones are tiny metal lumps that look equal parts blingy and classy and feel indestructible despite weighing next to nothing. Well done on that front.

Then the problems start. First of all, I'm not sure why the CL2 uses MMCX connectors instead of the ubiquitous 2-pin connectors. So far, Audeze has released five planar IEMs that use the standard 2-pin connectors, so it's clearly no restriction imposed by the driver. Perhaps the shells are simply too small—not that I know if that makes any sense—but whatever the reason, I think it was a bad decision. Especially when the two included cables driving up the price don't make much sense either.

For starters, two sonically distinct cables included in the same package should share a termination. Having one be 3.5mm and the other 2.5mm means that anyone with just a smartphone can't use one of the cables they're paying for, and even people that can use both cables won't be able to directly compare them. Further, the cables are much too long and the Y-splits are too far down, hampering portability; and the flexi-lamp-style ear guides are a clever idea that just don't work well in practice. Not to mention that whatever the jackets are made of generate so much friction with the chin sliders that it's almost not worth cinching them.

"But," I hear you saying, "stock cables usually aren't fantastic; why not just use an upgrade cable?" The thing there is, I would, but none of my upgrade cables are MMCX, because the only other popular company I'm aware of that uses MMCX connectors is Campfire Audio, and I don't own any of their products. The idea of using a different cable did cross my mind though, so I tried the CL2 with the stock cable that came with my Etymotic ER4XR. This is not an upgrade cable by any means, but it's an appropriate length, the chin slider works, and it doesn't really sound any worse or even different than the included cables.

Finally, the lightweight, diminutive shells conspire with the spinning connectors to frustrate any attempts at inserting the CL2 in any reasonable span of time, which is curious the first couple times, then seriously annoying forever after.

All that said, once fit is achieved, it is secure and comfortable. A solid selection of tips are included, and they're nicer than many no-name inclusions. Because of the tiny shells, you might need to use larger tips than you usually do, but that also means the shells don't stick out very much, and the insertion depth is good enough despite the short nozzles for appreciable isolation and a secure seal.


I really wanted to like the CL2. It's a seriously impressive piece of engineering, and it gets so close to greatness. However, as much as I want to, I can't let it off the hook for its failures, because there are just too many, and, collectively, they compromise the experience too much for a $1000 monitor. The CL2's sonics are its best feature, and they make a strong case: I heard Shure's KSE1500 at CanJam earlier this year, and it blew me away; meanwhile the CL2 sounds nearly as good for a third of the price, and without a permanent, proprietary box attached. That deserves credit. But other aspects of the CL2's design let it down. MMCX was a questionable decision at best, especially with subpar cables in the box. But even that would be an annoyance rather than a dealbreaker if the CL2 were tuned just a little bit better. As it is, the CL2 sounds nearly as good as the KSE1500, but in too much the same way, and Shure pulls ahead with that final layer of finesse. Not to mention that the arguably even better KSE1200 retails for $2000, and either Shure configuration can be had for even less used. Because of the above, I find it difficult to recommend the CL2. If $1000 is a concrete ceiling to your spend, and you'd swear on your grandmother's grave that the CL2's presentation or prepackaged Bluetooth solution is exactly what you need, go ahead. But for most of us, I'd give a well-deserved and respectful nod to an impressive effort on RHA's part, extend my wallet and patience a little, and snipe a used KSE instead.


Headphoneus Supremus
Pros: Tons of detail, great attack and decay, fantastic kit and build quality.
Cons: Doesn’t play well with all sources and gets harsh fast with compressed tracks.
In fairness I would award a 4.25 but the site lacks the ability.

I received the RHA CL2 as part of the North American review tour. Getting to try out earphones at this price point is a treat for me as it is well above my normal budget. Having said that, with the price point of the CL2, expectations are high. I have tried to stay out of the discussions surrounding this earphone until such time as I had a chance to listen to it. I will try and evaluate the CL2 as fairly as possible and words here are mine alone. I was compensated in no way, nor do I have any financial interest in RHA or any of its affiliates. After my time with the CL2, they were sent to the next tour reviewer.

Unboxing / Packaging / Accessories:

I almost always debate the need for this section as most unboxing experiences are pretty uniform. In this case, there is little doubt that the kit needs an unboxing and accessories discussion. The kit starts out as a book-box design. Once the outer cover is removed the book unfolds into 3 sections.

The left most section contains a 3.5mm single ended cable (copper) and a 2.5mm balanced cable (silver plate) in the upper compartments and a selection of tips on a carry card in the lower. The card has 7 silicone tips and 2 styles of foams on-board. The middle section of the box has a foam board with cutouts for the earpieces themselves and the Bluetooth cable and the right most compartment has the flight adapter, USB Cable, a soft case, and a folding travel case for the cables and accessories. A clip for the wired cables is also tucked neatly amongst the parts (with this being a tour kit, I am not 100% certain where it is supposed to be amongst the other goodies). The kit provided with the CL2 is as complete as any I have ever seen at any price point. Short of providing the DAP and source material, they put everything in the box and organized it very well to boot.


The earpieces themselves are a comma shape with a slightly blunted nose made by injection molding zirconium ceramics. Shells are made in two parts, (outer and inner) and while surfaces are glass smooth the seam between the outer shell and inner shell is easily seen and felt with a fingernail. The outer shell has RHA stamped into the housing and is tastefully understated while the inner shell has CL2 and either L or R in a circle. The right earpiece also has a red ring circling the mmcx connector for identification purposes. Nozzles are made of stainless steel and protrude from the lead edge of the comma with a slightly forward rake and are of what I would call normal length. they are not overly long, nor do they seem particularly shallow. I like the grills on the nozzles as they are one of those little custom touches that probably does little for sound but does everything for the eye when looking at them. The pronounced lip on the nozzle should make tip retention all but guaranteed as well.

The mmcx connectors are well implemented as they neither were overly brutal to manipulate as some recent examples have been, nor were they loose enough to worry about drop-outs, or disconnections due to movement during use as has also been a problem with others. While I am still of the opinion that perhaps the bi-pin connector is more trustworthy, RHA does a good job of showing that mmcx connectors can be well implemented.

Fit is very easy and I found no problems with size, but having said that, I did find a need to use a larger tip than normal as one side (R) wanted to seat considerably deeper than the left and initially caused me some problems. This is likely to be a function of ear shape and others may not find it to be an issue. For me, the CL2 is thin enough that it can rotate at the mid point so the nose seats deeper in the ear while the rear pushes slightly farther out than level. I haven't found myself lamenting an in-ear that was too thin, but in this case it just might be true that a bit of extra girth might well prevent that. Tightening the chin slider and carefully fitting the earhooks also helped.


Drivers in the CL2 are listed as a 10mm diameter 16μm thickness planar driver with a nominal impedance of 15Ω and a sensitivity of 89dB. This puts the CL2 in the middle ground where it can be driven by a phone but it definitely benefits from a bit of extra power due to the low sensitivity. (This is not an uncommon theme in planar drivers). That doesn't sound impressive, until you realize that the driver was developed in-house by RHA and represents the first time a planar driver has been fully enclosed in an in-ear design. Audeze and a few others have released what are called planar in-ears but in truth the driver is much larger and sits outside the ear with only the sound bores sitting in the ear. The CL2 fits as comfortably in the ear as any standard dynamic of BA design. I look forward to seeing RHA continue to advance this state of the art in planar miniaturization.


The cables bear some discussion of their own. Most IEMS don't come with this complete a set of cables even at this price point and all three of the cables are well done. First up is the standard 3.5mm TRS terminated single ended cable. The Jack is a straight model with a polished stainless housing and about a 1cm clear plastic strain relief at the exit. The cable is oxygen free copper in a two wire twist design up the splitter and single wire straight design above it. (Yes I know there are two wires on each side above the split, but to look at the cable you wouldn't know that). The splitter is also brushed stainless with the RHA logo on one side and a serial number on the other. Strain relief on the lower side of the splitter matches that on the jack while the upper side has shorter 2mm soft plastic strain reliefs to avoid interfering with the chin slider. The slider is clear rubber and requires good effort to move but not so much so as to worry one about the amount of stress being placed on the cable to move it. The cable terminates at the earpieces with a weighted earhook with a metal spring inside to help it retain shape followed by an MMCX connector housed in clear plastic. Honestly, the last 3 inches of cable do not appear to be of the same grade or quality as the rest of the cable and the earhook is probably my least favorite part of this package as it is unnecessarily large and cumbersome. Every time I put the CL2 with this cable (or the 2.5 for that matter), I had to readjust as they had loosened up and the earhooks wanted to interfere with my glasses. Were I to purchase this IEM, I would request an un-weighted version or simply replace the cable.

Second up is the 2.5mm balanced TRRS terminated cable which shares most features with the 3.5mm except it is silver plated copper rather than pure copper. Otherwise, construction is the same and repeating the earlier comments seems unwarranted.

The third cable in the bunch is the Bluetooth model. I kind of expected the CL2 to fall apart when we moved to this cable as I expected the cable to have trouble keeping up with the power requirements of a planar and Bluetooth having trouble keeping up with providing a good enough signal to really give the drivers something to work with. I was partially right. The band itself is of fairly typical behind the neck design which I am not a huge fan of but does distribute battery weight evenly and it was more comfortable than expected. One issue I did have was the exit of the cables from the body of the band has no strain relief and while fairly thick, it was already showing some signs of use on the tour. Under less stressful use, this may be a non-event, but I would prefer a more durable design. At least the terminations this time are standard earhooks with mmcx connectors and fit my ear better and interfere with my glasses less than the wired offerings.

On the functionality side, when first turned on a voice greeting announces how much battery life the unit has left which is a nice touch and seemed fairly accurate although I did find if I turned the unit on and off repeatedly I would occasionally get a different value (usually within 15% of the other, but it did vary). To pair the device, a long press of the power button puts it into the correct mode and the LED will blink the typical red/blue pattern to let you know. I had no issues with pairing with any DAP, phone, tablet, or laptop I tried the CL2 with.

Controls are on the right side cable and are very similar to other RHA offerings. The barrel is steel as used in the other cables with a rubber strip that covers the 3 buttons. The three buttons are Volume down/back, play/pause, and volume up/forward as you travel up the barrel. Its a fairly simple design, but it works reasonably well. The microphone on the reverse however was in a perfect position to rub on my shirt collar and made it less than stellar for use on phone calls. (Who uses a $1000 iem for phone calls anyway? I should be so lucky).

Battery life. Ok, so battery life is almost always over-stated and unfortunately I found that to be the case with the CL2 as well. RHA's website lists a 12 hour battery life which I found to be optimistic at best. I did find that I could use the cable for nearly an entire work-day (8.5 hours with a few breaks) without having to stop and recharge it, but would need to recharge before using it again. Still this represents extremely good battery life when the weight of the cable is considered, but I do think RHA may have fibbed just a touch on this part.


Having already alluded to the need to roll tips a bit to get the fit I needed, I can say that the CL2 came with quite a selection of tips and I found a set I could be happy with in the kit without looking outside. Tips included are two sets (SML) of dual density single flange silicone. (This is the way you get around saying Spin-fit if you didn't license the name). Also included in the kit are small and large double flanged silicone tips (which while usually my least favorite turned out to be exactly what I am using to do the sound notes on the CL2) as well as a couple pairs of medium sized T400 Comply foams. I have some Large T400s in my kit but thought they did little for the CL2 and thus stuck with the large double flange due to the positioning issue I previously mentioned.

Sound: (Sound Notes done with Large double flanged Silicone tips)

I had hoped the T-series tuning filters would fit the CL2 but it does not currently offer this. (Maybe CL3 will?)


Sub-bass on the CL2 is quite good in both quantity and quality. I was particularly impressed by how tight the sub-bass was and how well articulated it is. Walking bass lines are clearly rendered with no slop and no lingering decay. Mid-bass is in near equal proportion to the sub-bass with only a slight push forward while maintaining the same level of control. Overall, the CL2 is impressive in its ability to deliver a basshead worthy performance without feeling like a one trick pony that is all bass and nothing else. If you have friends that say "Bass doesn't have details" let them try the CL2 and then ask them if they still believe that. These do a good job of making music below 250Hz and not just noises.


This is the place where I normally talk about the degree of mid-bass bleed and the amount of warmth the bass contributes to the overall signature, problem is on the CL2 it has none that I could detect. The bass stays where it should and transition into the mids is nearly flawless with no perceptible bleed to discuss. The mids do show a push forward that starts around the 1kHz mark that plateaus around the 2.5kHz mark and stays at that plateau until a bit over the 5kHz mark as it exits the lower treble. This is the one place I struggled with defining the CL2. At times, that push forward of the mids gave vocals a nice intimate feeling while at others it could be unnatural and overly aggressive. The more I tried to find a commonality to what sounded good or bad, the more I returned to two factors. The first factor is source. The CL2 is better when paired to the Fiio X7 (ESS) that tends to be a bit dry and clinical in the mids than to the Opus #1S (CL 43198s) that tends to be a slightly warm anyway. Same for the AK70Mk2 - it sounded better when paired to the xDSD and used as a transport only instead of using the internal DAC on the AK. The second factor is source material. I found consistently that the higher the compression and less the dynamic range of a track, the worse the CL2 handled it. Seems the loudness wars have taken their toll on a lot of tracks and the CL2 does a bang up job of identifying them. Unfortunately for me, my collection is not devoid of those and I found several tracks that were just plain unpleasant as a result.

Once you know the limitations of the CL2 and pair it appropriately, the mids can be impressive. Detail retrieval is very good and micro-detail is better than most. Again the attack and decay speed prevent any slop and percussion in particular is well rendered and very natural sounding. Vocal realism is on par with the best I have heard in an in-ear although female vocals seem a bit closer to the listener than male due to the slight push of the upper-mids/lower treble.


As previously mentioned, the lower treble sits on a plateau forward of the rest of the signature mildly and then begins to fall off as it moves into the true treble. Those expecting the granularity of typical planar treble will be markedly disappointed as while the treble is not quite as detailed as the lower registers, it still manages good extension without going too far forward and reasonable detail without becoming harsh. Cymbals are well rendered and don't have the metallic clicky sound often associated with planar drivers, and enough air and sparkle exist to really contribute to an immense feeling of space.

Soundstage / Imaging:

This is the thing I find the most out of character of the CL2 of all its attributes. To remind people, we are discussing a planar driver (not known for gigantic stage in general), in a closed shell (another bad sign) with maybe 5ml worth of space inside the shell, and out of this tiny cavity with rock solid (literally) walls, we expect to hear a stage that is anything other than minuscule? Well, yes actually we do. The CL2 delivers in spades as stage is both wide and deep and has some height.

Imaging is very good which is helped by above average instrument separation and the previously mentioned attack and decay speed of the driver. I intentionally tried to feed the CL2 tracks that were overly busy to try and force it to image poorly or congest and as long as I stayed away from the previously mentioned issue with compression on some masterings, I couldn't make it get claustrophobic.

Sound using Bluetooth:

As previously mentioned, I expected the CL2 to lose some resolution when using the Bluetooth cable and it does, but not as much as I thought it might. I also found it less prone to the issue with harsh mids when using the bluetooth cable. (I have no idea what DAC is included in the cable as I haven't been able to find any details, but I suspect it to be something slightly clinical based on listening experience). In the overall, I think the CL2 ranks as the single best bluetooth earphone I have had the pleasure of hearing. Battery life was literally an entire work day.

Thoughts / Conclusion:

Honestly when I signed on to the tour, I expected the CL2 to be a technology tour-d-force and a way for RHA to show off what they had done to miniaturize a planar magnetic driver. I expected it to be somewhat flawed in signature as almost all things are and first runs tend to be even more so. I saw Bluetooth as a poor choice as it would either detract from the package if poorly implemented or add little to it if done right, and I figured it would be one I would happily pass along to the next reviewer while telling myself I had things in my collection that sounded at least as good and cost less. Turns out, I can be kinda dense sometimes. While the CL2 is a technology show for sure, its a good one. The CL2 earns high marks in build quality, comfort, kit, Bluetooth implementation, and Soundstage. When paired with the right sources and source material, it delivers exceptional sound quality. Some will have no issue with spending the additional money to surround the CL2 with the other components it needs to do its best work, others not. My own feeling is that the CL2 is a highly revealing (if at times over-zealous at it) in ear with a lot of redeeming features. Sure, I'd be happier if they found a way to tune the mids to play nicer with less than perfect source material, but I am not unhappy with it as it is now and I'll be more than a bit sorry to see it go.
Agree on bass. People always say the juju is in the mids, but for me the bass is the emotional foundation of any song.


1000+ Head-Fier
RHA CL2-9.jpg


RHA is a relatively new audio company out of the UK (specialized in earphones) that is looking to expedite their market status with a pivotal flagship IEM. The CL2 isn't just another lofty expensive pair of capsules stuffed to the gills with balanced armature drivers. RHA instead put all their eggs in the planar magnetic basket. And it seems to have paid off. There's not another pocketable headphone in sight that can not only claim this kind of driver tech, but also house it in a closed, sound-isolating design.

But like with anything new in audio, fancy tech-talk aside, the ultimate question comes down to how they sound. This synopsis fires off the crucial details of RHA's high but not top-end priced, planar magnetic CL2 in-ear headphones.

RHA CL2-1.jpg

The Rundown
The CL2's standout appeal is its envelope-pushing driver tech, but that's not the only special thing about its package. The unboxing experience is also unlike anything I've seen before. RHA went all out. The box unravels to elegantly present a slew of accessories. There's enough praise by the inclusion of an optional balanced (2.5mm TRS) cable along side the standard 3.5mm one, but there's shockingly also a Bluetooth neckband to make the CL2 "wireless" if desired. An add-on accessory like this would typically set you back an extra +$100. RHA's care for the CL2, and its importance for the company, really shows.

RHA CL2-2.jpg
The CL2's unraveling box reveal is the best presentation I've seen for an earphone. RHA does not skimp.

RHA CL2-5.jpg
Digging in is an organizer panel with soft zipper carrying case and collapse-able organizer panel.

  • Class-leading generosity with its included accessories
  • First-rate quality across the board
  • Small and comfortable earpieces
  • Detachable cable design (MMCX standard)
  • Amazing imaging and dynamics
  • Top-notch detail, clarity, and decay

  • Cables don't have the most premium feel
  • Memory wire (ear route) is too long
  • Upper midrange can sound unnatural/metallic
  • Higher treble detail is lacking

What it's like to use

RHA CL2-27.jpg

  • The form of the earpieces follow suit of many high-end earphones (pod shape, MMCX connector, and around-the-ear wear) but the devil is in the details. The uniformly glossy ceramic shell mimics the elegance of the individual Sennheiser IE 800. But RHA takes it up a notch by mixing in zirconium dioxide, which may sound like unmeaningful technical babble but isn't in this case. The housing feel rock solid and have a little premium heft to them.
  • However, more consequential is the dimension of the earpieces. They're not just tiny in size but also thin (another plus of using a single and thin planar magnetic driver). This translates to an effortless fit in the ear. What's more, you're able to push the ear tips deeper than usual, increasing the success rate of an appropriate seal.
RHA CL2-22.jpg
The metal nozzle is a pretty standard size and length, meaning that there's friendliness with other tips out there.

RHA CL2-3.jpg
The three ear tips RHA includes are different sizes of single flange and double flange silicone and comply foam tips (screened interior).
  • RHA's silicone tips are a good quality. They have more of a dome shape than bullet (wide bore), but still achieve a good reach based on our comment above. The material leans more on firm than soft. I wish it was more in the middle. Flexibility makes it easier to get a seal, but then if it's too soft, isolation would be compromised. Overall, these tips are decent.
  • The two supplied cables look great, with transparent sheathing that eye-catchingly shows off the twisted strand makeup, but underwhelm in practice. The shrink wrap is this thick, bouncy rubber, which is good for tangle resistance but not for feel. Its feel doesn't keep up with the luxurious earpieces. But the length is notable, and I appreciate the tough stainless steel y-split (though, a bit heavier than it sound be) and audio jack elements.
RHA CL2-4.jpg

The cable with the standard 3.5mm TRRS jack is made of oxygen-free copper (OFC), while the balanced option uses a Ag4x silver coated material.
  • However, what I disliked most is the overbearing memory wire. They're greatly moldable execution is fine, but they're unnecessarily long. So unless you have huge ears, you'll feel the ends dangle under your ear lobes, and it additionally looks unflattering. But it's something that can be looked past. There isn't a compromise to comfort or usability here, and quite the contrary actually.
  • The supplied wireless unit is thankfully not an afterthought. It functions well, though, not the best wireless neckband from an ergonomic standpoint. When donned, the earpiece wires are a bit long and dangle with movement. While the neckband is thin, completely flexible, and comfortable, I still wish it was a simpler apparatus (like a one-piece bridging cable or pendant design). Less is more with earphones. As expected, sound quality takes a little hit. Specifically, some depth and clarity is pushed back, and low-level hiss is audible. That said, the impact is minimal compared to the wired connection (aptX support helps). It's honestly hard to complain when you get the flexibility of wireless at no extra cost.
RHA CL2-16.jpg
The wireless configuring isn't compact but bendable and lightweight.

RHA CL2-7.jpg
The wireless band sports the essentials: status LED, power button, and USB-C charging port (kudos for RHA not using the older microUSB standard).
  • I had no expectation when I went to RHA's booth at IFA 2018 to give the CL2 a first listen. To my surprise, it left blown me away and couldn't wait to get my hands on a review unit. After a good month with the CL2, the importance of time to truly assess a headphone's performance is exemplified. I still feel the CL2 sound excellent and special, as my initial impressions suggested, but it turns out that it's not a straightforward conclusion.
  • The imaging capacity of the CL2 is quite stunning. This is what caught me in the beginning, and what I continued to take most pleasure in. This is the closest I've heard an in-ear sound as full as an over-ear headphone. And it's not just a party trick, dynamics and soundstage are there with it. Instruments surround you, and at times have this pop like they reach and touch your ears. It's a sublimely engaging and fun experience.
RHA CL2-15.jpg

The CL2 sound fantastic even out of a well-equipped smartphone. You don't need a powerful amp, though quality definitely benefit out of my dedicated Mojo or Micro iDSD Black Label DAC/amps.
  • There's no recess such like that of a V-shaped sound signature to hold the CL2 back. All the ranges are present and full. It's refreshing to get a bold bass and crisp treble without a compromised mid-range. The impact of guitars and expanse of vocals is at the heels of my beloved Shure SE846.
  • The quality of bass decay isn't something I paid much attention to before the CL2. In the right track/moment, the range, clarity, and smoothness within a note's coming and going is beautifully rendered. The minuscule details the planar drivers capture is a godsend for the analytical ear.
  • However, here's where I must hit the brakes. The CL2 listening experience is unfortunately not a straightforward one. At first listen with the fresh unit, I was actually taken aback compared to my initial impressions. It sounded notably bright and shrilly. Not so much to ruin the experience; I could still hear the stellar elements I praised above. But in passages in my music that really hit on the upper half of the spectrum, an un-overlookable harshness was prevalent.
  • Research unveiled some interesting notes. To start, RHA supplied a basic frequency response for the CL2:
RHA's CL2 Frequency Curve.
  • The peak around the 2k-6k exactly goes along with what I noticed. RHA commented on this, saying that they settled on this tuning because this upper mid-range sounded overshadowed by the lower frequencies without it. They wanted driver's quality and excitement in this range to also shine, so they pushed it.
  • The concern is that it doesn't take too much of a boost for this range to become harsh, and unfortunately in the case of my ears, I hear that this limit was crossed. While no where near unlistenable or unacceptable, there's a definite unnatural, metallic essence in higher-end instruments and vocals (especially female) in this range. Depending on presence in the track, it can sound shrill and fatiguing.
  • Several CL2 owners on Head-Fi have discussed this, and there's a consensus that considerable burn-in tames the upper midrange's response. To give the benefit of the doubt (especially given that this is new driver tech; I'm generally a bigger believer in brain burn-in than physical), I ran them 300+ hours. I can attest that the harshness does slightly calm (happened at roughly the 100 hour mark, but I didn't notice much of a difference thereon). The CL2 definitely became less fatiguing for me. However, burn-in (even brain burn-in) didn't smooth out the metallic shrill quality of the range for the most part. I can still hear it after considerable burn-in. It's my opinion that RHA pushed this aspect of the driver too far. Note that different ear sensitivities will have different opinions about this questionable tuning; it's best to test drive the earphones if possible.
  • I also noticed, thanks to a comparison with the Sennheiser IE 800, that upper-end treble detail gets dropped off. This is more of a minor gripe, as there are a few that can match the IE 800's top-end clarity. Don't entirely worry if you're a treble-head, between the upper midrange and high treble end, there's notable crisp and clean detail to enjoy.
The Gallery
RHA CL2-6.jpg RHA CL2-8.jpg RHA CL2-10.jpg RHA CL2-11.jpg RHA CL2-12.jpg RHA CL2-13.jpg RHA CL2-14.jpg RHA CL2-17.jpg RHA CL2-18.jpg RHA CL2-19.jpg RHA CL2-20.jpg RHA CL2-21.jpg RHA CL2-23.jpg RHA CL2-24.jpg RHA CL2-25.jpg RHA CL2-26.jpg RHA CL2-28.jpg

Final Thoughts
Despite a couple critical criticisms, I still consider the CL2 something really special. RHA hit so many high marks with its first go at a closed, planar magnetic earphone. It's an analytical listener's dream. If it wasn't for the upper midrange peak that plays a little too close to the driver's limit, these things would be so darn close to "perfect". The lower end is so accurate and juicy and the midrange is full and energetic. If RHA can refine the upper half of the spectrum a bit more on in the next version, it'll give top-end and more expensive in-ears and whopping run for their money. Keep up the ambition, RHA.

As originally seen on TheSynops.com.
Nice review! You may want to burn the unit in for 200 hours before any critical listening...
I burned it in for 400+ hours before writing this up.


Headphoneus Supremus
Pros: Everything apart from the weird mid-centric boost in the frequency response
Cons: Weird mid-centric boost in the frequency response
Acknowledgements and Disclaimers

I'd like to sincerely thank Colum and the rest of the good people at RHA for kindly allowing me to be part of the North American CL2 tour. The CL2 used for this review was loaned to me and was passed on to the next reviewer at the end of my week-long review period.

Any impressions from the measurements in this post are inferred at the reader's own risk. No measurement will tell you exactly how you'll hear, as our hearing is unique to each of us. Measurements presented here are raw (uncompensated) and should only be used to make relative comparisons and not direct comparisons to other measurement rigs.

Initial Impressions

RHA are a relatively young company, but with some good pedigree behind them. You might know them from their very underrated T20(i) IEMs. At least, you should know them for that reason - the T20s are great headphones that sound way better than their price tag would suggest. So I was super-excited at the prospect of seeing and hearing their new CL2 - the world's first proper planar-magnetic in-ear monitors. (Ok, I guess, technically, Audeze got there first with their planar-magnetic TIE Fighter head-accessories, but Audeze's iSine/LCDi4 planars aren't isolating at all and they're huge and they look ridiculous. RHA have managed to engineer a small, isolating planar IEM that looks infinitely cooler than the iSines or the LCDi4.) Rather than just add more off-the-shelf balanced-armatures into yet another multi-BA IEM, RHA have really innovated something different and something special here - a single planar-magnetic driver in a small, ergonomic, traditional IEM shell:


Right out of the gate, things are looking good - the packaging and presentation look premium and they come with an impressive set of accessories:


Fit, seal, isolation, comfort, profile and aesthetics are all top-notch with the CL2. There's really nothing I can fault here. Kudos to RHA for understanding we don't all want to have something the size of golf balls sticking out the sides of our heads. Also, whether by luck or thoughtful design, the nozzles are precisely angled for my ear canals, so that the buds themselves sit perfectly in my concha bowls. That's a surprisingly rare find for me.

The accessories included are impressive and are actually useful. Included are a variety of silicone and (Comply) foam eartips (I had no issues achieving a good fit and seal with either type), a 3.5 mm single-ended and a 2.5 mm balanced cable and a Bluetooth neck-band. The cables appear to be of high quality and though I don't always enjoy memory wire, I had no particular issues with these. So far, so good.

I do own a few pieces of kit that support balanced output via 2.5 mm TRRS sockets, and almost all of my headphones are terminated with a 2.5 mm balanced connector. With that being said, a lot of the time I end up using a 2.5 mm -> 3.5 mm dongle in order to listen via my V30, Shanling M0, Questyle QP1R or my Chord Hugo 2, none of which support a balanced output. When I first heard Chord's excuse for why they didn't support balanced outputs, it sounded like that - an excuse. But I've since done a 180 on that thinking. The fact is, the single-ended output of my Hugo 2 sounds (and measures, in every respect, including channel separation) better than any of my balanced-output sources. There's certainly an argument for balanced cables, but my current thoughts are - if the single-ended implementation is done well, you really don't need a balanced connection for an IEM. So while I greatly appreciate RHA giving us the option, I'm actually looking forward to the day when all my devices will only have single ended connections and I won't need to feel like one of Apple's unfortunate victims by carrying a dongle with me everywhere.

Sound Impressions and Measurements

Now for the not-so-good news. In the first few seconds of listening to this headphone I knew something was off. It sounded like the all-too-common lower-treble peak, so I switched from silicone to foam tips and that helped a bit, but something still sounded off. So I then put the CL2 on my measurement rig. Yikes RHA - that's a very unconventional tuning! The following measurements fairly closely match measurements from RHA that I was able to find online. My measurements were made using a 711-compliant coupler using REW and are presented here raw, with no added compensation other than that for the mic and sound-card. It appears that RHA's measurements were also raw:


There are some discrepancies in the high and low frequency extremes, and I give a list of possible reasons for that, along with measurement procedures and lots more disclaimers in this thread: https://www.head-fi.org/threads/audio-measurements-on-a-headfi-budget.893084/. The discrepancies at the lower frequencies are most likely due to my coupler & mic. I suspect the differences around 9 kHz are most likely due to RHA's out-sourced measurements using a newer GRAS hi-res coupler, which imposes a strong (but not necessarily physical) damping at the half-wave resonant frequency of the ear canal. Listening with foam tips to a frequency sweep with a tone generator gave the impression of a more even response between 6-10 kHz, i.e., most likely some kind of average of the two measurements. YMMV in this regard, because of your own ear canal resonances and impedances. However, the most significant feature of the FR is in close agreement in both curves, and this is the large bump in energy between about 2-5 kHz, followed by a substantial drop in the treble. There's always the possibility of unit variation, but the channel matching between L and R buds was fair and both show the same effect:


I contacted RHA to ask about measurement tolerances and whether they felt the frequency-response in this region was indeed indicative of all CL2s, and not just this particular tour unit. This was their reply:

The graph we provided is from the golden sample, which is kept in our manufacturing centre for comparison versus units from the line. Our tolerances are to +/-1db; the above should be a fair representation of anything coming off the line (and they are tested to this standard).

So I think this rules out any specific defect in my tour unit in that regard. The CL2 really is supposed to have that bump between 2-5 kHz. Hmmm... Now, eartips can make a difference. As shown below, foam tends to roll off the treble, which was why I switched to the foam tips - for me, the CL2 sounds better with foam tips (I suspect some of you may also find the ~9 kHz and ~13 kHz peaks with the silicone tips a little strident). For this reason, all other measurements here were made only with Comply foam tips. The following figure shows the differences with the two types of eartip:


As you can see, foam eartips have the most pronounced effect in the treble region. They do lower the mid-range bump too, but only by a pretty small margin. The reason for the tuning in the CL2 is very likely the same reason behind diffuse-field compensation (explained more at that http link above). Since birth, our brains have had to compensate for the fact that, because of our ear canal resonances, we receive a boost at our eardrums in the 3-4 kHz region. Ironically, we often get a dip at ~4 kHz when we start to lose our hearing because those cilia have taken a heavier beating during our lives - so older folk might actually prefer the CL2's tuning. But the theory for some level of mid-range boost applies to everybody: when you take away the ear canal resonance mechanism by shoving something deep into your canals, you want to account for that boost in the IEM tuning. Or do you...?

Our brains are amazing at adapting to skewed input data. I'm 99% convinced that 99% of burn-in that people hear is nothing more than our brains adapting to skewed input. (There's a classic example of this here: https://www.theguardian.com/education/2012/nov/12/improbable-research-seeing-upside-down.) I have measured differences before and after burn-in, but in all cases those differences were so small that I would never be able to successfully A/B them with a week or two gap in between. I accept that after a sufficiently-extensive CL2 listening period, there's a possibility that one's brain may adjust to the sound. But even if that were the case, would you really want that? Your brain and ears are already tuned to the natural sounds of everyday life. A good pair of headphones should be tuned to you, not the other way around.

Even using foam tips and accounting for the ~9 dB peak shift from a diffuse-field compensation, the rise in SPL between 2-5 kHz is still about 7 dB north of neutral. There is also a substantial drop into the lower treble (RHA's own measurements show a 30+ dB delta from 4 kHz ->10 kHz, although, as mentioned above, I suspect things won't actually be this bad for most listeners).

Varying the insertion depth will shift the location of the resonance peaks somewhat to the left or right. As shown above, ear-tips will alter the roll-off in the treble, and marginally alter the amplitude of the mid-range. Adding some significant resistance to the cable might drop the mid-range bump by another tiny margin, but IMHO, none of these effects are going to make an appreciable dent in a mid-range bump this large. While some level of mid-range boost is a feature of most IEMs (for the reasons discussed above), the level of this bump in the CL2 is an outlier with respect to any other headphone I own. At 4 kHz, it is more than 5 dB larger than the bump in the ER4XR, which is a deep-insertion IEM and so, arguably, has more reason for such a boost (the CL2 cannot insert as deeply into the ear canal as the Etymotic IEMs):


To some degree, I don't think there's necessarily a right or wrong with FR. Some people may love this CL2 tuning. But it would be interesting to know if a majority of people would prefer this large of a mid-range boost. This isn't an easy thing to test, because even a parametric EQ is a fairly crude tool without knowing exactly where those peaks fall, given one's particular eartips, ear canals, hearing sensitivities, etc. But I tested a couple of curves on the parametric EQ in UAPP on my V30, for example:


I found I needed to drop that mid-range bump by around 8 dB to get something that sounded roughly normal to my ears. After quickly toggling this EQ on and off... well, I can't imaging anybody would prefer the non-EQ'd version. But let's find out... You can vote here:


BTW, please don't vote unless you've actually had a decent amount of listening time with the CL2, and have actually tried to EQ out some of that mid-range bump.


Measurement of total harmonic distortion is not entirely straightforward, because THD varies with both frequency and amplitude (it generally gets worse as you crank up the volume, causing greater movement of the driver). For this reason, it's not really helpful to put too much significance on any single number. But given the level of effort needed to make multiple THD measurements at different amplitudes and considering how much I was paid to write this review ($0.00), I measured THD at only one SPL, which is near the higher-end of my usual listening volume. These are flat (Z-weighted) THD measurements for the CL2 at 80 dB:


These are very good - the CL2 has extremely low levels of THD. (Lower even than those of my all-time favorite headphones - the Shure KSE1500 electrostats. However, bear in mind that the KSE1500 has a very quiet amp and in practice, you might also have audible N from the DAC/amp you're using to drive your CL2.) I did detect a slight noise floor from the CL2 using my QP1R, but I'm insanely sensitive to hiss - I suspect most people wouldn't be bothered by this.

Impulse Response

I anticipated that a planar magnetic driver would exhibit a faster response than a balanced-armature, and certainly faster than a more traditional dynamic driver, (if Xelento's Tesla driver can be considered traditional?) but that's not the case here. The CL2 driver doesn't seem to have a lot of damping and exhibits quite a delayed response with some notable ringing, suggesting a larger/heavier/slower-moving diaphragm:





If you think you can't differentiate transients down to such a small number of microseconds, check out the following (there's a readme in amongst the test tracks):


You might be surprised at how low you can go. You should certainly be able to discriminate lower than 1/(2*your_hearing_threshold_in_Hz).


The CL2 is nominally rated at 15 Ohm, however, they have a relatively low sensitivity (89 dB/mW), so you will need a reasonable amount of juice to power them with a comfortable amount of headroom. Their impedance curve is impressively boring, i.e., almost completely flat apart from a tiny bump at 4 kHz, but its deviation is nowhere larger than 1 Ohm:


I had no problems driving the CL2 from my smartphone, but then again, my smartphone is an LG V30 :) For those that know the V30, the CL2's ~15 Ohm impedance triggers normal-device mode, which for me, was plenty loud enough, but there are options to trigger aux and even high-impedance mode, should you want even more power (https://www.head-fi.org/threads/music-apps-tips-and-tricks-for-the-lg-v30.868978/).

Shanling M0
LG V30
LG V40
FiiO X7 Mark II
Questyle QP1R
Chord Hugo 2

These are all excellent, clean-sounding recordings with good dynamic range:

Alan Parsons Project - The Fall of the House of Usher
Big Big Train - The Leaden Stour
Camel - Broken Banks
Cosmograf - The Hay Man Dreams
Daft Punk - Give Life Back to Music
Glass Hammer - She, A Lonely Tower
Janusz Carmello - Joy Spring
Jethro Tull - Thick as a Brick
Liszt/Hungarian State Orchestra - Les Preludes
Pink Floyd - Dogs
Radiohead - Let Down
R.E.M. - Fall on Me
Rimsky-Korsakov/Montreal Symphony Orchestra - Sheherazade
Seal - Deep Water
Simply Red - Enough
Steven Wilson - Drive Home
Yes - Awaken


The CL2 is a beautiful-looking IEM that ticks almost every box you could think of in an IEM wish-list - with one big exception. It has a weird, mid-centric-boosted tuning that you can't do much about. The CL2 has very low levels of THD, but its FR just overwhelms everything else about the listening experience and this is something people might either love or hate. I'll just be diplomatic here and say that I didn't love its FR, which was really disappointing for me considering how good this IEM is for ergonomics, comfort, fit, isolation, etc. EQ helps, but isn't a panacea when most of your listening kit doesn't have a parametric EQ. For the price of the CL2, one shouldn't need to resort to EQ. I have a lot of respect for RHA's design team though and I see a lot of promise for the CL3. I would be all over that in a heartbeat if it were to give us a more conventional (flat, neutral or gently U/V-shaped) frequency response, or at least an option to tune it more in that direction.

A good initial trailblazing effort from RHA. I will certainly be first in the queue to check out the CL3...
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Excellent, solid review , csglinux!
Your findings confirm my impressions. While most other owners were preferring silicon tips, I preferred comply foam tips for my CL2.
Their FR is far off from neutral, as you rightly showed. In spite of this clear shortcoming with their tuning, I do love them, I find it great to have a planar sound in tiny and closed IEM! I mainly use them at work for listening to metal, usually from an AK player, and alternating with the neutral Focal Elegia.
Thank you for this informative review. Any chance you are able to export the CL2 raw measurements (either your own and/or RHA's official measurements) as a CSV file? I would like to create my own convolution filters using REW. Thanks!


1000+ Head-Fier
Pros: Extremely good bass response, wide soundstage, very high resolution, industry leading build quality that makes a mockery out of many competitors, very comfortable shell design, good set of accessories, well designed Bluetooth cable, priced cheaper than its main competition, 3 year warranty
Cons: Problematic midrange tuning/not an all rounder, some roughness in the treble, MMCX connectors, no 100% safe anti-earwax system, no sound tuning filters like on some previous RHA products, no mobile app to upload EQ settings to the Bluetooth cable

This review is based on a loaner unit I got from RHA from their Europe Head-Fi tour. I got the opportunity to audition their IEM for around a week before sending it to the next one in line. Thank you RHA for the opportunity! I have no prior experience of any RHA products, although I’ve almost bought the T20 on a few occasions. As for RHA (or any audio company), I have no financial or personal ties to them and actually did not even keep contact with them much during the time I had these in order to stay as neutral as possible. In addition I purposefully did not read any reviews before writing this up (just saw a few impressions posts on the main CL2 thread, but even there I’ve maybe spent 20 minutes tops). There is no financial incentive to write a positive review. Communication with RHA over the package shipping was a pleasure, they were always quick to reply and professional. All listening was done either at home wired via 3.5mm to RME ADI-2 DAC via its IEM specific port or portable with the included Bluetooth cable.

The official RHA CL2 Planar website is: https://www.rha-audio.com/ca/products/headphones/cl2-planar (I will be referring to the frequency response chart posted there in this review, although I just noticed there's a more accurate one posted in one of the other reviews)

Although I am using the word review throughout this article, please keep in mind that this is all written based on a week of listening and I would have preferred to listen to these more extensively, but it’s a tour with a fixed schedule and I wouldn't have wanted to delay it anyway. What I am trying to say is this: consider these extended impressions instead of a traditional full review (which in my experience needs a month or so of steady listening to form a good solid opinion).

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Since reviews without any context are (if you ask me) often at the minimum quite confusing and at the worst pretty useless, here is a list of some of the IEMs I’ve owned and eventually sold on in the past: Sennheiser IE 80, IE 800, IE 800 S; Shure SE 530, SE 846; Ultimate Ears UE 900; Fischer Amps FA4E-XB, Rhapsody; Jays Q-Jays (current version); EarSonics SM64; HIFIMAN RE-600S. Comparisons are thus from memory, but I'm pretty confident this does not effect things that much as many of those IEMs are ones I used for a very long time.

Why are all these now gone? I intend on going wireless only when it comes to IEMs. For me portable audio needs to be truly portable and nothing is more portable than wireless. Home setups are a different matter entirely, but on the go I want something that gets out of the way and disappears. This is actually the main reason I applied for this tour: the CL2 seemed to me to be one of the ground breakers when it comes to finally getting high end sound quality in a wireless setup. I might be missing some products, but from this point of view I see it its main competition being the AKG N5005 and Beyerdynamic Xelento which both come “wireless ready”. Both are however more expensive than the CL2. Unfortunately I haven't heard either, so I can't make any comparisons there.

As for my tonality preference, out of everything I've heard I consider the Sennheiser HD 600/650 and the Focal Clear to be the best tuned headphone audio products thus far. In the IEM world the Sennheiser IE 800 S takes the crown. From this you may guess that I value a smooth frequency response with mids and treble that do not have any major spikes. Ideally a headphone needs to be able to handle all kinds of music. Being genre-specific is generally a bad sign: the original Sennheiser HD 800 likely being the most famous example.

Now I know many audiophiles are at the very least, well, let’s say conservative when it comes to accepting wireless audio. After all lossless is considered the standard and yes, there is a small difference between modern lossless and lossy files. The difference however in my experience is definitely not as big as is often claimed and and the very least it’s very difficult to hear on anything most mainstream music. Classical, vocals and other genres with minimal compression are a different topic entirely though, in those the difference is much easier to hear. In any case the AAC (and others) codec of today is not the same as five years ago and huge advances have been made in both cods and Bluetooth technology. In other words the sound quality gap between wireless and wired is getting smaller day by day.

The CL2 however strikes the ideal balance: it caters to the traditional audiophiles by offering a wired option (two actually, one cable is for balanced use which many no doubt will appreciate) along with the wireless, so everyone can make up their own mind which one they want to use. This is just my guess, but I’m betting a lot of people will start using these wired and eventually slowly move into using them almost exclusively wireless...


I always knew RHA had build quality locked down. It’s pretty obvious: just look at the build materials, online videos and so on. In other words I expected to be impressed with the unboxing and surely enough I wasn’t disappointed. It screams high end and quite frankly makes a mockery out of many competitors. The way the box opens has a bit of an Apple style vibe with the IEMs being in the middle with their cables disconnected. Let’s check out the accessories first: there’s the wireless cable, two wired cables (one copper 3.5mm and one silver-planted 2.5mm balanced), a carrying pouch, an airline adapter and a selection of tips (more specifically a mix of double-flange, silicon and Comply ones in different sizes) on a metal tip holder that works surprisingly well.


The first surprise however were the IEMs themselves. They are much, much smaller than I thought they would be judging by the pictures. The form is quite close to the classic Shure/Westone (+ Earsonics SM64) style, which is actually my favorite shell style. It’s a classic with a good track record. You can already guess how well the shells fit my ears (and I’m pretty sure they will fit most people really well; better than many other designs), but what isn’t apparent in the pictures is how nice these feel. The RHA website mentions that these are built from ceramics and these do indeed have a similar feel as the Sennheiser IE 800, although the CL2 feels more solid, weightier in a positive way and somehow tougher. This is quite a surprise considering the CL2 weighs 9 grams vs. IE 800’s 8 grams without a cable. These are basically built like a tank and feel more or less indestructible, although I have no idea how well these can take hard hits against concrete and so on (with IEMs this expensive that shouldn’t really be happening though). My guess is that the ceramics layer is thicker than on the IE 800 series since they also feel quite cold before warming up. Or it could just be because the material is different: the ceramics they are using here is zirconium. Ceramics in general is probably the ideal material for IEMs since it is extremely stiff and durable, the downside being that it’s expensive to work with and is thus only seen in higher end products.

As for the design, the CL2 looks high end yet minimalistic. It won’t gather any unwanted attention on the subway like perhaps the Beyerdynamic Xelento would. Now aesthetics is obviously a very subjective topic, but personally I’m a big fan of this approach. They don’t draw attention to themselves, look good with any clothing style and aren’t really that divisive compared to something more brash looking.


As for the cables, the wired ones I feel are bound to divide opinion. They are quite thick, heavy and the colors are a far cry from the minimalistic and understated look of the IEM itself. Some will love them, others will feel they are too thick and difficult to handle (and may not be a fan of the aesthetics). I personally fall into the latter group, although I must admit the silver cable to me looks much better than the copper one. Hopefully RHA will sell the silver one in a single ended configuration someday?

The wireless one is a different matter entirely: it follows the same minimalistic design philosophy as the IEM itself and well, it just disappears. The design is beautiful. The plastic/rubber mix feels nice to touch, it doesn't feel cheap in any way and is just something that looks like it belongs with the CL2. It initially feels a bit heavy when you pick it up, but when actually wearing it the weight distribution is so good that it basically disappears. The wires coming from the battery section are also just the right length and do not to hang out in an annoying way. It's also worth emphasizing that it has a USB-C port for charging. Finally... Audio for whatever reason has been very slow to adopt USB-C despite its obvious advantages. The Chord Hugo 2 for example still uses Micro-USB, which if you ask me diminishes the value of the product somewhat. Micro-USB has a habit of breaking down and is just very flimsy feeling in general. You’ll find none of that with USB-C plus the cable orientation doesn’t matter anymore. The cable charges quickly and I didn’t have a problem with running out of power during the day. Never experienced any audio cutouts either and the pairing process with an iPhone X was a breeze. I unfortunately forgot to measure how long the cable charge lasts, but hopefully someone else from the tour can do that since it’s probably something a lot of people want to know.

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These IEMs use MMCX connectors. I’ll be honest with you: I’m not a fan. I’ve had a UE 900 and Shure SE 215 that both used this connector and developed audio cutouts to the point where I found using them very annoying. However on the other hand I had the Shure SE 846 for quite a long time and they never had a single issue despite using the same connector. I’m hoping the CL2 will be similar, but in addition to potential cutout issues my main grievance with this type of connector is the basic swiveling function they have. In my experience it doesn’t improve finding a good fit, it makes it more difficult as you have to adjust them more often. With a classic 2-pin connector like on the EarSonics models you just bend the memory wire to suit your ears and forget about it: since it won’t swivel they will always feel the same when you put them on. This is however a theme that divides opinion a lot, there are also a lot of fans of this connector. That being said, however one feels about MMCX in general, fact is that these have more or less become a standard in the industry so from that point of view I understand RHA going this way. For me it’s definitely a minus though; even if they never develop cutout issues, I just don’t find MMCX cables as comfortable/solid feeling (with over ears IEMs) compared to the traditional 2-pin connector that’s used in many custom made IEMs and also some universals like in the EarSonics ones.

As for the included tips, well, with universals it’s always down to luck. When I saw the tip selection I was pretty sure I wouldn’t encounter any issues, but to my surprise I could not get a decent seal with any of the double-flange or silicon tips. Only the Comply ones seemed to seal, and those aren’t tips that I would normally use just because they are slow to put on, wear out fast and because of that just aren’t all that suitable for portable use if you ask me. I'm not sure, but the nozzle looks quite similar to the classic Logitech style on UE 900 so I was left wondering if perhaps the UE 900 tips would fit these well. Unfortunately I don’t have them anymore so I couldn’t test. Don’t get me wrong, the Comply foams feel very comfortable once they settle in, but for me IEMs need to be used with silicon tips so you can quickly take them out and put them back in without having to replace tips that often. Hopefully RHA will expand the silicon tips selection in the future, although I have to say it’s not currently bad at all (instead it's better than on many competitors like the IE 800 series); I was just unlucky.

Unfortunately the CL2 does not feature RHA’s tuning filters. This has two downsides: first of all if the stock tuning isn’t to your liking you are out of luck (unless you EQ them, but EQ is not something I am willing to do with portables unless there's a product specific app that uploads the choices to the IEM itself so they work universally), but also there is now no 100% safe ear wax filter (except on the Comply tips which have one, but that’s another matter) on the IEM itself. On an IEM this expensive I would have prefered to see some system that is 100% safe. There is however a metal spiral part that likely helps keep ear wax away from the grid section.


Once I finally pressed play I was instantly impressed: bass was very deep and punchy as expected, but it never overshadowed the mids. Resolution seemed high and soundstage was far larger than I expected from a closed design planar driver. Even the treble extension – traditionally a weak spot with planar drivers – was very good. However as I listened to different songs I noticed there was kind of a rough feel to the sound as if the drivers hadn’t really settled in yet. So I left them to burn in and continued later. It turned out this was a smart move: these were apparently straight from the factory without much (or any) burn in and they did indeed settle down a lot. So a note to all future listeners: burn these in for at least 24 hours before starting to listen. Oh and for the record I’m not even a big believer in burn in, but planar drivers seem to be an exception (I’ve had similar experiences with full size planar headphones; balanced armature IEMs on the other hand never seem to need any burn).

That being said, first impressions in audio are notoriously unreliable. If something really wows you the first time you listen to them it may even be a bad sign: the HD 800 is a good example. It’s probably the best case study of a product that creates an almost unbelievably good first impression when listened to which carefully chosen music, but then in the long run many end up selling due to the treble spikes (or lack of bass). In my experience high end audio products typically have at least some major flaws, it’s more or less to be expected. Finding an all rounder with a smooth frequency response is extremely rare and that's the ideal to aim for. That’s why the Sennheiser HD 600/HD650 series are still so popular even after all these years: they may sound unremarkable at first, but they have no serious flaws and offer some of the smoothest frequency responses on the market. The IE 800 / IE 800 S are also interesting in this regard: the original IE 800 has too much bass and treble for a lot of people making it good for outdoors use in noisy areas, but a bad for indoors use. Or a genre specialist for pop/hiphop/electronica, depends on who you ask… The IE 800 S took a different direction and toned down both the treble and bass leaving a very smooth frequency response, but on the other hand some will feel it lacks the “fun” factor the original had. But let’s finally get to the more in depth sound quality parts of this review...


Planar drivers aren’t really generally known for being the most resolving ones. They have a lot of other virtues like class leading bass performance, but raw resolution in my experience just isn’t one of them. That’s why I was very surprised to notice that these are actually very resolving IEMs. Not on the same level as the IE 800 S for example, but clearly superior to your average 300-400 euro price range IEMs. Now I haven’t heard that many planar headphones, but I would say these are more resolving than the Audeze LCD-2 Classics (which I’ve owned) or likely even the HIFIMAN HE-1000 I’ve auditioned. That being said, I’m not completely sure if this subjective feeling of a high resolution is entirely down to “real resolution” or if it is partly enhanced by the boosted upper midrange. My guess is that the truth is somewhere in the middle: that this is an exceptionally resolving planar driver, but the tonality is also designed to provide some added “fake” sense of detail. More on that in the midrange section though.

The thing I expected the least out of these was hearing a wide soundstage. I know many disagree, but I’ve never heard a planar that didn’t sound at least somewhat claustrophobic and closed in. There’s none of that here, which is almost a miracle considering these are not only a planar design, but in addition to that a closed shell design. To put things short: these have a wide and tall soundstage that often makes you forget that you are listening to IEMs. Not many IEMs pull this off, so this is definitely one of the high points here. The only minus when it comes to the soundstage is that the depth is not on the same level as the rest (for example the IE 800 series is clearly superior in this regard). Instrument separation is also very good: above the typical cheaper IEMs, but not best of class. Out of everything I’ve heard that award still goes to the IE 800 series. All in all considering the technology being used here and the closed design the soundstage performance is exceptionally good.


So far so good… Now this part you probably already guess what I’m about to write. This is a planar driver after all and bass is simply what this technology does the best. This is where planar drivers excel and one of the main reasons many find it very difficult to go back to dynamic or balanced armature drivers after getting used to planar bass performance. That being said, there were also a couple of surprises here. Let’s start with what you probably do expect: yes, the bass is ultra clean, tight and goes very deep. However it also fast: subjectively there isn’t a lot of extra decay, so instead it sounds tight, tuneful and never bloated.

The surprising part here that there is no artificial bass quantity boost, which is usually common with planar drivers because it's a nice way to show of the technology. You won’t find that here. These aren’t bass cannons at all and instead go for neutrality. This doesn’t mean the bass quantity is lacking per se, but these do not have the added bass boost some IEMs have that lead to a “fun” sound tonality that often suits genres like hip-hip/electronica well. That being said while I didn't try EQ with these, planar drivers typically respond well to EQ so on a home rig at least it should be easy to add a couple of dB of sub bass for that extra kick. The official frequency response chart (although very smoothed over as official ones always are) seems to support impression. All in all these probably have the cleanest, fastest and deepest bass I’ve ever heard out of an IEM. Personally I would have preferred to have a bit more sub bass boost though, but unfortunately that option is only there with EQ. The inclusion of tonality adjusting filters would have helped here.


This is where things for me got problematic. Now I’m a fan of smooth, linear midrange that does not have any major dips or spikes. Our ears are also the most sensitive in this area too. For me this part in the frequency response makes or breaks an IEM. In my experience IEMs that stray too much from linear here can often sound shouty, fatiguing and the realism of the vocals suffers as well. I’ll start with the good news: due to the neutral tuning the bass never, ever intrudes on the midrange. It doesn’t matter how much bass is in the mix (or how deep it goes), midrange will always stay clear of bass influence. In fact it’s not just a matter of not intruding on it, but parts of the midrange are actually boosted on this IEM to bring vocals forward. I’m again referring to the official frequency response chart on the RHA website: notice the rise beginning from the midrange (500Hz to 2kHz) and then the clear spikes in the upper midrange (2kHz to 4kHz). This spike in the upper midrange is often used in headphones and IEMs among other things to boost the sense of detail (however one can argue that it’s fake in a way), but nothing comes free: it can also make sibilance worse or just sound unpleasantly shouty/sharp on certain material. Unfortunately the midrange tuning style in the CL2 is not something I generally like and I have to say that in many aspects this proved to be a deal breaker for me. Sibilance wasn’t the issue, but the CL2 had the latter issue on many songs. On a home rig I would definitely want to EQ this down.

As it generally is with headphones with similar midrange tonality, it really depends on what you are listening to: in many albums there are no problems and the tonality may even sound subjectively better than a more neutral approach, but on many albums I found the sound too fatiguing/piercing after a while. Overall this breaks the CL2 as an all rounder for me. I would personally have preferred a more linear midrange (no upper midrange spike) at the expense of less perceived detail. Generally speaking this kind of tuning (at least to my ears) is more of a problem with mainstream genres than audiophile ones though, so it partly depends on what kind of music you listen to the most. Note however that I am probably a lot more sensitive when it comes to midrange: for example I found the Shure SE 846 midrange to be too shouty/edgy as well (not as much, but to an annoying degree). All this being said, there are of course also a lot of people who prefer boosted upper mids, so it all comes down to personal preference.

The resolution on the other hand continued to impress: vocals were often very realistic and when an album is mastered in a way where the upper midrange spike doesn’t offend, the results are often stunning. However due to the dB level difference between lower and higher mids some vocals can sound a bit off/muddled depending on where they hit on the frequency response. This is another downside to the chosen midrange frequency response tuning.


Planar drivers can’t do treble well. That’s at least the stereotype and to my best knowledge getting treble right is one of the main challenges when working with a planar driver (vs. getting bass right on a dynamic). Well, this one defies the odds here and is definitely not your typical Audeze LCD-2 Classic or even the Shure SE 846 (where the treble seems to fall off a cliff pretty fast). Now the treble here isn’t the smoothest or most detailed out there compared to the highest level of competition (IE 800 S for example is on different level), but it is very impressive for a planar driver and a critical part in creating that awesome soundstage. The CL2 treble is nicely extended and that's something I wasn’t expecting to hear at all. The is a slight roughness in the treble that isn’t apparent in high end balanced armatures or dynamic driver IEMs, but it wasn’t something that annoyed me much. Due to the slight roughness the resolution here didn’t sound as it was quite on the same level as in the midrange and bass, but the difference wasn’t drastic enough to make it stick out too much.


This one is tough… From the moment I opened the box I wanted to love them. They do so many things right: a superb wireless cable design, industry leading build quality and comfort, they're priced fairly and of course the quality impresses in many ways. On the downside however it goes with the MMCX connectors and the only tips that worked for me were the Comply ones (just bad luck; I doubt many will have this problem). It’s main issue however to me is the midrange tuning that artificially boosts the sense of detail, makes certain material sound shouty/fatiguing and for me that simply breaks it as an all rounder. The treble is also slightly problematic, but that is something I would gladly take in return for getting freed from the traditional claustrophobic planar driver sound.

Would I recommend it? Yes if you have a preference towards this kind of tuning, are ok with MMCX connectors and know from past RHA products that the tips fit you well. For others I would say it’s an IEM that you need to audition before making a decision or buy from a place that accepts returns. Then again that’s what I would say of more or less every expensive universal IEM out there. To sum things up: add 1+ star if the midrange tonality is to your liking and you have nothing against the MMCX connector type. Personally however I believe IEMs need to be all rounders and I place a high value on frequency response smoothness so for me this is unfortunately (despite all its virtues) a pass. I just wish RHA would have kept their sound tuning filters technology or perhaps supported an app that can upload EQ settings to the bluetooth cable. That could have solved the most pressing issues for me (except for the Comply one, but fit with universals is down to luck).


Headphoneus Supremus
Pros: Build quality - Intense accessory kit - Comfort - Bass quality
Cons: Timbre and veiled mids - Noisy cables (unless you use the chin cinch)

Today we're checking out an exciting new earphone from Scottish outfit RHA, the CL2 Planar.

The newest trend in in-ear monitors (iems) seems to be planar drivers. Audeze started us off last year with the iSINE10 and 20 which were basically a 30mm planar driver set within a Tie Fighter-inspired shell. Not the most elegant thing in the world, but they looked pretty awesome to me and seemed to review well, particularly with the DSP equipped Lightning cables in place.

RHA has taken a more refined approach, further shrinking down what is a traditionally fairly large driver type to something extremely compact. At only 10mm, and in a gorgeous zirconium dioxide (ceramic compound) shell very reminiscent of that used on the late-2016 CL1 Ceramic, the CL2 Planar provides a more traditional iem experience without the ergonomic challenges inherent to larger drivers.

How did they do? Let's find out.


The CL2 Planar was sent over as part of RHA's review tour. After a week (and a couple extra days) it was mailed off the the next reviewer in line. The thoughts within this review are my own and do not represent RHA or any other entity. No financial incentive was provided to write this review. At the time of writing the MSRP for the CL2 Planar was 899.95 USD or £799.95.

You can check out the CL2 Planar here on RHA's website: https://www.rha-audio.com/ca/products/headphones/cl2-planar

I generally prefer a couple weeks with a product before feeling 100% confident in my opinions. Had I spent more time with the CL2, my thoughts might be slightly different. The below review is based on around 18 hours of wired use, and 3 or so hours with the Bluetooth neckband.


The majority of my listening was done through the balanced out of my Radsone ES100 acting as a USB amp for my ASUS FX53V laptop, or, with a Shanling M0 sourcing music through my TEAC HA-501 desktop amp. I found the CL2 to sound best through the HA-501 with damping setting on 'low'. This seemed to reduce the upper mid bump, making the CL2 sound more natural.

Personal Preferences:

I listen primarily to various EDM sub-genres (liquid drum and bass, breakbeat, drumstep, etc.), hip hop, and classic rock. While I enjoy a variety of signatures in my headphones I generally lean towards slightly warm with elevated treble and sub-bass, an even and natural mid-range response, with reduced mid-bass. The HiFiMan RE800, Brainwavz B400, and thinksound On2 offer examples of signatures I enjoy.

  • Driver: 10mm planar driver
  • Frequency Response: 16Hz-45,000Hz
  • Sensitivity: 89dB/mW
  • Impedance: 15 ohms
  • Max/Rated power: 2/10mW

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Packaging and Accessories:

Every RHA product I've had the pleasure of using has come in some lovely packaging, and the CL2 Planar is no exception. This particular unboxing is pretty cool. Starting with the exterior sheath, on the front you have a glossy, high quality image of the right ear piece along with the usual branding. On the back RHA goes over some features like the 16μm thickness planar driver, that it can be used wired and wireless, and that the housings are injection molded. They also show off the included Bluetooth module and that it comes with both a regular 3.5mm cable, and a 2.5mm balanced cable. It's a bit of a bummer they didn't include one terminated with a 4-pin Mini-XLR connector like they did with the CL1. Those of you out there with the DACAMP L1 will need to settle for using the 3.5mm connector, unless you already have an MMCX cable terminated with Mini-XLR. Removing the sheath reveals the black box within that opens like a book to reveal two more panels. Flip those back to start revealing the contents. In all you a pile of gear;
  • CL2 Planar earphones
  • Ag4x silver coated cable (MMCX – 2.5mm balanced)
  • Braided OFC cable (MMCX – 3.5mm)
  • SecureFlex Bluetooth neckband (MMCX)
  • Flight case
  • Soft carrying case
  • Stainless steel ear tip holder
  • UBC C charging cable
  • Flight adapter
  • Dual density single flange silicone tips (s/m/l x2)
  • Double flange silicone tips (s/l)
  • Comply Tsx400 foam tips (m x3)
  • Sports clip
Overall this is very nice unboxing. It certainly feels premium enough to reflect the asking price, a thought supported by the quality and quantity of the accessories. Both regular cables feel expensive, as does the Bluetooth neckband. The flight case is really cool and seems to hold all your cables securely enough, though I appreciate they still included a more traditional soft case for when you want to carry a more basic kit with you.

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Build, Comfort, and Isolation:

The CL2 Planar's build is nothing short of phenomenal. The injection molded ceramic shells feels amazing in the hand and look the part too. The RHA branding on the outside of the shell is bodied colored and looks to be a part of the molding process and as such if flawlessly integrated into the design. On the inner half of the shell CL2 and the L/R markers look to have been cut in afterwards. The cleanliness of the cuts is impressive with well-defined edges and a very sharp look. Nozzles are a separate steel piece with a distinct lip for holding tips on. There is a unique swirling grill protector over mesh that we also saw on the CL1.

The included cables have a dense, clear sheath with the wires within showing off a candy-cane styled pattern twisting throughout. Strain relief at the compact steel straight jacks is prominent and should do a good job of protecting the cable from damage if tugged. Above the steel y-split is a chin cinch that effectively holds the place you set it on the cable. The sheath is a touch sticky which helps with that. Leading into the MMCX ports is a unique style of memory wire using a spring instead of a simple strand of flexible metal. The Whizzer A15 Pro uses a similar design and I found it to be more durable over repeated bending when compared to traditional memory wire, though it has clear limits on the shapes you can achieve. The CL2's memory wire was much the same, though it was able to achieve a useful arc that kept the cable behind my ear at most times. It was a touch springy (no pun intended) and with exaggerated movement would send the cable up and over the ear. I also found both of these cables quite noisy when not using the chin cinch. It is recommend to slid the cinch up no ensure cable noise is kept in check, and that the cable stays exactly where you want it.

Overall comfort of the CL2 Planar is outstanding. I was easily able to wear these for hours without any discomfort. The shells are extremely smooth and completely free of sharp edges. The low profile, rounded shape, and compact size let them nestle into my outer ear without any fuss. This is how a an earphone should fit. With a lighter cable these would completely disappear in the ear, for me at least.

Isolation I found pretty good, even with the basic silicone tips. The shell doesn't seem to be vented anywhere and as such, outside noise is limited to a dull murmur. When typing, only the highest pitch of a clacking key could be heard. In the local Tim Horton's, I could easily listen to my music at my regular listening volumes without the need to crank the volume to compensate for the going ons around me.

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Bluetooth Module:

I did not spend a ton of time with this module, but the time I did spend with it showed it to be a quality inclusion. Pairing is as easy as every other wireless device nowadays. Press the power button, hold it until the indicator light starts flashing, then locate the neckband on your device. Select it and you're good to go. When turned on, the module plays a tune then a pleasant voice announces how much battery life is left which I thought was a really cool feature. Limits guess work if the battery life indicator on your phone, or other device, doesn't scale with the actual remaining life of the battery or if you simply don't have one.

The neckband itself is constructed primarily of a very flexible rubber. Normally I hate this style of module because they feel quite cumbersome draped around the neck, and bounce all over the place when you're walking. This one works well. It has some weight to it which combined with the flexible materials means it slumps comfortably around the base of your neck and stays put. You can always tuck it under your shirt too. The cables that protrude out the front leading to each ear piece are not relieved which is about my only complaint here. Still the sheath is pretty dense and feels tough enough to last a good while before you ever experience any issues. Leading into the MMCX ports are some traditional preformed ear guides. I personally preferred these over the more interesting looking ones on the other cables since they always remain in the correct shape.

Lastly, media controls are not built into the neckband, but a three button module part way up the right cable. If you've used a mobile version of one of RHA's earphone sin the past, you'll be familiar with this controller. The body is steel with a rubber strip laid out over the buttons with small indicators (+, -, and a recessed dot for the centre button) telling you where you need to press. It's a good module that works well.

When it comes to sound, this thing did well. It is more than powerful enough to bring the CL2 Planar up to some high volumes if that's your thing. The sound signature is unchanged from wired use, and I didn't notice any distortion or other quirks in the few hours I listened. If you prefer to listen to your earphones wirelessly, you're not giving up anything when using the module. @Kitechaser Source was the Shanling M0 mentioned in the "Source" section above.

IMG_5119.JPG IMG_5127.JPG IMG_5132.JPG


Tips: I stuck with the stock silicone tips for the purposes of this review since they were comfortable and sealed just fine. Foam tips were used as well, but I prefer the more energetic sound of the silicones.

Outside of reading that people were really liking what the CL2 was putting out, I wasn't sure what to expect in terms of signature. What I found was that it has a well balanced presentation through the bass and lower mids, a spike in the upper mids, dropping back down through the treble. This results in an earphone that sounds quick but stiff, slightly cold but with a touch of warmth in the bass, and with a fair amount texture and detail.

Treble on the CL2 is prominent but I never found it exaggerated to the point of discomfort, though when not driven adequately it can sound quite harsh. There isn't a lot of shimmer and sparkle here either leading to chimes, cymbals, etc. that comes across a bit dull and frigid. Take King Crimson's “Starless and Bible Black” as an example. The detail and clarity is excellent though with all the instrument's textures and nuances shinning through. I also love how quick the decay is, making the CL2 an outstanding pairing with complicated tracks.

The midrange on the CL2 has a very breathy presentation, reminding me a lot of the in-house designed balanced armatures used by EarNiNE. This is really evident in Fuego's vocals on Dillon Francis' “We the Funk (feat. Fuego)”. His vocals take on an almost raspy tone through the CL2. It sounds good, though he should have a smoother, more liquid presentation. That leads into my biggest issue with the CL2. The mid-range just does not sound quite as it should. The upper mids are too forward and yet at times come across veiled, giving the presentation a very odd timbre. Since I'm always trying to get my wife into higher end audio, she gave the CL2 a go. Given she used to sing and play piano, she's got a good ear. After a couple tracks, she took them out with the comment, “Sometimes it sounds like they're singing through a blanket.” Echoes my sentiments exactly.

Posted by RHA in the CL2 thread

The CL2's low end is the most enjoyable aspect of it's presentation to my ears. It is far from being a bassy earphone but extension is outstanding, as is the sub-bass presence and quality. It reminds me alot of Massdrop's Planamic in speed and way it moves air, though it's not nearly as exaggerated here in the CL2. Listening to Havok's “Fatal Intervention” the CL2 easily divides each kick of the drum without sounding muddy, let alone challenged. On The Prodigy's “Rebel Radio”, the bassline has an impactful punch to it while all the grimy texture of their gear shines through. Kavinski's “Solli” shows off the impressive sub-bass depth and just how much rumble this earphone can output. This is one flexible, articulate driver.

Sound stage I found slightly larger than average with excellent depth that gives tracks a very layered feel. Imaging is precise with smooth channel to channel transitions that give off a good sense of space and accuracy. I didn't have the opportunity to test them with gaming, but I suspect they'd be pretty decent for shooters.

Overall, I find the CL2 Planar a fairly technically competent earphone that outputs reasonable detail and clarity in the treble and bass amidst a spacious presentation. Unfortunately, the occasionally veiled mids and more importantly, off-kilter timbre, tended to take me “out of the zone” much of the time I listened to them. Through the HA-501 it was less of an issue. Had I more time to spend with the CL2, I would have a taken an EQ to the upper mids to see what could be done to improve performance. It certainly is not a poor sounding earphone, it just isn't particularly impressive either. I hope RHA continues to develop the driver since it clearly has potential.


Select Comparisons (volumes matched using Dayton iMM-6):

Campfire Audio Polaris (599.00 USD): Polaris has a strong v-shaped signature with brighter, more sparkly treble and deeper, slower, but no less textured bass. Mids have a more intimate presentation on the Polaris with the CL2 setting the artist further back from you. Both have a breathiness to the mids with slightly off timbre, though clarity is better on the Polaris. While the CL2 has a deeper sound stage, the Polaris shows greater width with more space between instruments. Imaging and separation is better, though the CL2's deeper stage helps it with layering. Overall, I find the Polaris the more exciting listen. It has a more lively presentation as a result of it's more powerful, v-shaped signature. CL2 is a bit more subdued and mellow, better for long listening sessions.

HiFiMAN RE800 (800.00 USD): The CL2's low end extends deeper and has more impact than the RE800. Mids have similar presence with the CL2 having a touch more body, less warmth, and less detail. Treble is leaner and shows greater emphasis on the RE800, especially in the brilliance region which making it a fair bit brighter. CL2 has a more spacious presentation with greater depth and improved layering. Imaging seems slightly more precise on the RE800 while instrument separation is quite similar. Overall, RE800 is a little lighter sounding, quicker, and more intimate vs. the more balanced, meatier sounding CL2. I find the RE800 more natural sounding, especially if you EQ out some of the treble. Clarity is also slightly improved over the CL2, specifically in the mid-range.

Final Thoughts:

The CL2 Planar looks and feels every bit the flagship earphone it is. The zirconium dioxide shells are visually stunning in person and are nearly flawless in their construction. The comfortable shape allows you to wear the CL2 for hours without issue. The packaging and accessory kit are second to none and in my opinion, add a ton of value to the product. Especially the cables. Each of the three cable options could easily be sold on their own for a pretty penny given the construction quality, and the performance of the Bluetooth neckband.

Sound is the only area where I felt the CL2 Planar fell short, which is a bit of a disappointment given RHA's development time for such a compact planar driver. It shows off some impressive technical prowess, but that doesn't doesn't quite make up for the unnatural sounding mids, especially when pitting it against the competition. The treble on the other hand is rife with clarity and texture. The bass is too, providing one of the better low end experiences I've had so far. The depth it reaches and the articulation it shows is outstanding. While I enjoyed my time with the CL2, it was less because they blew my mind with how they sounded, and more because of how great of an experience they were elsewhere.

If you're looking for a new flagship, one that provides a unique sound experience that is backed up with an insanely flexible and decked out accessory kit, the CL2 is worth checking out.

Thanks for reading!

- B9Scrambler

***** ***** ***** ***** *****

Some Test Tunes:

Aesop Rock – The Impossible Kid (Album)
Hail Mary Mallon – Are You Going to Eat That? (Album)
King Crimson – Lark’s Tongues in Aspic (Album)
King Crimson – Starless and Bible Black (Track)
Supertramp – Crime of the Century (Album)
Infected Mushroom – Legend of the Black Shawarma (Album)
Gorillaz – Plastic Beach (Album)
Massive Attack – Mezzanine (Album)
Fleetwood Mac – Rumors (Album)
Run the Jewels – Run the Jewels (Album)
The Prodigy – The Day is My Enemy (Album)
Tobacco – screw*d Up Friends (Album)
Felt – Felt 2 (A Tribute to Lisa Bonet) (Album)
Michael Jackson – Thriller (Album)
The Crystal Method – Grace (feat. LeAnn Rimes) (Track)
Jidenna – Long Live the Chief (Track)
Skrillex – Ragga Bomb (Track)
Big Grams – Run for Your Life (Track)
Funkadelic – Maggot Brain (Track)
Aesop Rock – Fishtales (Track)
My experience with the veiled mids is that they went away with burn in. I noticed it as well on first use. Timbre seems fine with my set, again that may be a burn in problem. As it's a planar, RHA recommends 100 hours of burn in.
@Carlsan While it certainly would have been ideal to let them play longer, I didn't have the luxury since this was a tour unit. It received 20-30 hours of use prior to being shipped out to, according to RHA. Add to that the ~21 hours I used them plus whatever time they spent on the "burn station" playing in the background while I was at work. If burn in is a factor, I'm sure impressions will improve as the tour goes on.
Copper cable, and a 100 hours of burn fix all the issues raised in this review.
I would comfortably pick this over any other planar, IEM or headphone, almost all single driver iems.
In my humble opinion, this leaves the much beloved Andromeda in its dust. END GAME IEM FOR ME.
Listen to it again after a 100 hours if you get a chance.


Headphoneus Supremus
Pros: Transparency and clarity
Beautiful transients
Very fast with great PRaT
Open natural soundstage
Non fatiguing
Great bluetooth neckband implementation
Isolation and comfort
Cons: Upper mids walk a fine line so depending on cable, source or mastering can border on harshness
Highs lack a bit of sparkle
Revealing, not everything will sound great, you’ll only get what’s there!

RHA is a independent audio company based in Scotland. Their mission statement is « to transform the way people interact with sound, technology and each other. » Ambitious goal perfectly embodied by their experimental line (CLx) of product started with the CL1 with its ceramic driver and now the planar CL2.

The CL2 is built around the most compact planar magnetic driver ever engineered - « a 10mm transducer containing a magnet array, a planar coil, and a 16µm diaphragm ». So it’s the smallest planar IEM ever built and is also the only closed back contrary competitors like Unique Melody ME.1 and audeze iSine line up. As RHA states in his CL2 announcement, « Conventional dynamic drivers use a single ring coil to create sound - using a solid plane results in a huge step up in control and response; and a massive drop in distortion. This is particularly important for more complex, detailed music that moves across the dynamic range; using treble and harmonics alongside deep bass. »

RHA didn’t stop with the driver, and looked for the best housing possible for the CL2 and they chose Zirconium. ZrO2 is more than aesthetically great and durable. Ceramic has excellent acoustic properties, the inside of the CL2 is designed to carry audio waves from driver to ear without distorting it. This is not a premiere, as Sennheiser IE800 featured similar material for the same acoustic reasons and the upcoming Sony IER-Z1R will also go down that route.


The CL2 has a premium package and bundle, it contains the following accessories :
  • a single ended 3.5mm OFC Cable
  • a balanced 2.5mm SPC 4 wires Cable
  • a SecureFlex Bluetooth Neckband
  • a Sports Clip
  • a Flight Adapter
  • a magnetic Foldable Travel Case (to fit both cable and the bluetooth headband)
  • a Carry Pouch
  • a USB A to C Charging Cable
  • A Stainless Steel Ear Tip Holder with
    • 6x Silicone Dual Density Ear Tips (S/M/L)
    • 2x Silicone Double Flange Ear Tips (S/L)
    • 3x ComplyTM Foam ear tips (S/M/L)
  • Impedance: 15 ohms
  • Max/rated power: 2 / 10mW
  • Sensitivity: 89dB
  • Frequency range: 16 Hz – 45,000 Hz
I have purchased and paid the full retail price for the CL2, this is not a sponsored review.


The CL2 are fairly small IEMs, that require deep insertion and some tip rolling to find the best isolation and SQ. I can’t insist enough on how important this is for the CL2 to provide the best experience. Your mileage will vary, but I have found wide bore tips to be the best selection : Tennmak (grey and black), Sony hybrids, JVC spiral dots or symbio W all good candidates. My own favorites are rather unconventional EarFoam Audiophile tips from the Flares PRO. I found the bundled dual density have a stem smaller than bore and therefore affect the sound.

Once you have found your tips of choice, you’ll be able to enjoy the best SQ, isolation and comfort. The CL2 are highly comfortable IEMs to wear for long period of times.


The CL2 have a balanced signature with very natural bass, a very articulate, clear and transparent midrange and well extended but non fatiguing treble against a pitch black background. The overall presentation is very lifelike, although a slightly warmer tone would probably make for an even more natural timbre. The vocals are slightly forward, making for a highly engaging presentation.

The soundstage is very wide with good depth and height, but most importantly very coherent with a precise imaging. There is something very natural reminiscent of open back headphones (despite the seal, a remarkable feeling of openness) in the CL2 soundstage. This along with a small lower treble dip and zero distorsion makes the CL2 non fatiguing. I found myself pushing the volume much more than any other IEM I have owned, even more than I would do with a full size open back. Last but not least when playing very fast and complex tracks the CL2 seems to be taunting you to throw anything you can at it. It’s very very fast across all the frequency range.

The CL2’s bass are among the most natural I have heard, it’s a clean bass with good extension and no mid bass boost. Despite being extended, it’s not a hard hitting bass but rather a well rounded bass with a lot of texture and details. It’s also very fast, in fact one of the fastest bass I have heard. Attack is snappy but smooth and decay is a quick as it comes when called for, there is a lot of control there.

Depending on tracks and music genres the bass can vary greatly in quantity, a testimony of the CL2’s transparency to the recording. It features an ability to provide some amazing sub bass with top notch control and zero distorsion. On the flip side, those are a minority but on some recordings it can sound anemic and lacking impact and weight. Listen to « Oi-1 » from Biosphere and the intro bass gets deep with no hint of any distorsion. Same thing can be experienced with James Blake « Limit to your love », 56 seconds into the track. Deadmau5’s « Strobe » also shows how good the CL2 can kick with fast attack and snappy recovery. In a different genre, Kat Frankle « Too Young » shows beautiful textures of the drum.

The CL2’s mids are tuned with clarity in mind, with a gentle dip in the lower mids and a boost in the upper mids. This is a very clear sounding IEM, there is a lot of air between instruments and the CL2 is able to provide a lot of details with great resolution. I find myself picking the CL2 quite often when I listen to Jazz, where it's able to feature its great qualities. For instance, 30th anniversary at the pawnshop from Arne Domnérus was a sublime experience.

There is just one caveat : the mids tuning on the CL2 walk a fine line. Some recordings will push the CL2 into agressive mids territory, others recording will daze you with the clarity of those mids and remain silky smooth. I almost never EQ but applying some -1/-3dB EQ in the 3-6Khz range is definitely helping. Interestingly even on harsher recordings or more revealing sources, without EQ sibilance has been avoided on all but more sensitive albums.

Vocals are just forward enough to make for an engaging presentation, while not falling into intimate territory, the soundstage still features good depth and instruments are not recessed either. I just wished for a bit more lower mids for male vocals sometimes lack the gusto and power I’d like them to have. Female vocals, on the other hand, really shine.


The CL2’s treble are somewhat of a mixed bag. Providing a lot of air to the CL2 signature thanks to good extension and detail, contrary to the mids, they seem to have been tuned to play it safe with a dip in the lower treble maybe removing too much sparkle. The benefit is a less fatiguing signature and no sibilance, but the CL2 could have provided more excitement there.

This being said upper treble are a treat, the CL2 clearly shows its ability to handle fast transients and sparkle in the upper treble region.

Source, cable and tip matching

At 15ohm and 89dB, the CL2 is not the easiest IEM to drive but it’s still fairly easier than similarly spec’ed IEMs like the Final E5000 that despite being more efficient at 93dB is much harder to drive. I believe the CL2’s clarity greatly helps in this regard.

The CL2 is a transparent IEM and with the upper mids tuning walking a fine line, source will make a big difference in how much of this can be an issue for you. When I first got the CL2, I mainly ran it with DX200 and AMP8. This was a bit disconcerting listening experience as the DX200 is quite transparent and my experience (with smooth IEMs such as VE8 and Phantom) has always been detailed but smooth. Not so much with the CL2, where it could verge on harshness at times. This is much less the case with the ZX300 and even more on the 1Z. I suspect it would be even more apparent with revealing DAPs such as SP1000 or SE100. I would therefore recommend a warmer source.

The stock cable is of good apparent quality but a bit dated in its design, with very rigid earhooks (not necessary for the CL2’s weight and deep insertion) and thick cable insulation. Both the 3.5 and .25 balanced cable are fairly stiff and uncomfortable. More importantly, I found the upper mids and treble had an off timbre with the stock cable, making instruments sound metallic. Swapping the stock cable for the Hansound Zen corrected the timbre issue.

Last but not least, the CL2 is provided with a bluetooth neckband that - despite not offering aptX HD - is a very good alternative for the CL2 on the go. The neckband is smartly tuned with a gentle mid bass boost (useful in noisy environment), a pleasing lower mids bump giving it a tad more body and warmth and the upper mids are slightly tuned down loosing some clarity along the way but gaining in the smoothness department. Treble are emphasized a bit to compensate for the mid bass and lower mids boost. I think it’s smart as you will probably not be in critical listening mode when on the go. The biggest surprise comes from the driving power of the neckband, which is much better than expected as you’ll hardly need to ever cross 60-70% of max volume. Well done RHA!


With the CL2, RHA has ventured where no one had gone before (yeah, I am a Star Trek fan), building both the smallest and the first closed back planar making it a very interesting and unique proposition for many of us. Does it live up to its promises? I think it does and fully deserves its place among the likes of AKG N5005, Sennheiser IE800S and Final FI-BA-SS.

If you’re looking for a balanced natural IEM with great clarity and transparency that doesn’t compromise on bass, is very natural sounding and engaging, then you might have found just the right IEM for you. If you’re keen on treble sparkle and/or sensitive to upper mids you should make sure this won’t be a blocker for you as its lower treble are tuned conservatively while upper mids are more daring. If you use the CL2 mainly on the move with the neckband, this shouldn’t be an issue.

@Kitechaser Well always subjective to the reviewer isn't it? I don't believe in X being better than Y in absolute terms, always relative to the signature and personal preferences. Those IEM you quote are quite different than the CL2 in terms of their signature, they have different strength as well. To me the CL2 have a few weaknesses (so yes, not 5 stars for me) I don't pretend to own any truth, it's five stars for you and that's what counts :)
I didn't mean to attack you, I can see how my reply might have come across as shrill.
I just think like all the iems i listed, the CL2 have their strengths and weaknesses. This is the nature of single driver iems.
I feel like the things the CL2 does well are done so well, that they outweigh what little faults they have.
Some genres of rock is where the issues pop up, outside of that, they are a pleasure to listen to.
We just disagree on a few things, no big deal. :)
As I said on the CL2 thread, I have tried the UE900 tips with the CL2 and it's changing the game in the bass department, much more kick and the deepest insertion alters the frequency range. I'll revise the review once I get some time with the combo


500+ Head-Fier
Pros: Timeless, classy design
Small form factor
Very well balanced sound
Excellent sound quality in all major aspects
Cons: Stock cables are thick, maybe too much for some
For this review, I wanted to start off in an unusual way. While I could write a typical introduction, I found it a rather boring approach. I thought “what is the reader most interested in?” and I found a simple answer. It is the central question of all audiophile inquiries: how does it sound? So the largest part of my review focuses on how the RHA CL2 perform as in-ear monitors. After the listening impressions I also shortly discuss the aesthetic design and the stock cables the CL2s ship with, before coming to my conclusion.

This review does not provide any measurements or technical details that the manufacturer, RHA, does not already provide on their website.

Music selection

I chose the following five albums as the main listening material for this review:

(Artist: album)

Hans Zimmer: Interstellar (original movie soundtrack)
Herbie Hancock: Round Midnight (original movie soundtrack)
Kenny Werner: New York – Love Songs
Sade: Diamond Life
Zawinul Syndicate: World Tour

All albums are 44.1khz / 16bit (redbook) flac files that originated as CD rips.

I also listened to high-resolution audio tracks, but did not find that they offer a better insight into the capabilities of the CL2 than the standard redbook format.

Sources + amplifiers

iBasso DX150 portable digital audio player, with amp6 amplifier module
DDDAC 1794 (see profile for details about configuration) + Corda Jazz headphone amplifier

Listening impressions

Sade - Diamond Life

A classic of the 80s, Sades “Diamond Life” is not only full of hit tracks, it’s also to this day a well recorded and produced album. I have a weak spot for women with lower voices and for those who don’t sound “girly” (no offense to women who have a different kind of voice, but when it comes to singing, I have my preferences and I offer zero apologies), and the CL2 makes this album sound as seductive as it possibly can be. Drums and percussion have a nice punch to them, making me move with the rhythm while I write these lines. From the album opener – famous “Smooth Operator” - to the last track (“Why can’t we live together”), the CL2 are capable of portraying the music with excellent detail and “snap”. Even without measurements, I am confident in my assumption that the CL2s have very good impulse response.

Herbie Hancock - Round Midnight

Herbie Hancock fully deserved the success he had with the “Round Midnight” movie soundtrack. It’s recorded and mixed pretty much perfectly and composed in a way that both the layman and the expert jazz listener can appreciate it.
On “Body and Soul”, the CL2 deliver the music as if I was at a private concert. Instrument size is very realistic and the tone is beautiful. I suspect that writing more would just distract from the fact how great this album is over the CL2s. I have a hard time bringing my thoughts to paper as the music grabs all of my attention again and again.

Hans Zimmer - Interstellar OST

Listening to "Mountains" was an absolute thrill. The ticking "clock" sounds very tangible, the tension of this piece rising with every "tick... tock.." as the music goes on a more and more frightening pace. When it unleashes all its glory at around 2:02, it's a jaw-droppingly majestic moment.
On lesser setups, this track sounds forceful, but often somewhat muddy and congested, portraying brutality rather than overwhelming greatness. Over the CL2, it's a shockingly captivating sound, giving me goose bumps every single time.

Kenny Werner - New York / Love Songs

On "First Light / East River", the album opener, it's oddly not the music that grabbed my attention at first. The CL2s are so resolving that I can perfectly hear Kenny Werner inhale before he starts to lay his hands on the keys. On other setups I wasn't even able to realize that this can be heard so clearly before the piece begins. Once the CL2s allowed me to expand my attention on those before unhead details, it became a very intimate listening experience - more than it already was before.
"New York - Love Songs" is a great study in complex harmony and chord voicings, as Kenny Werner is a masterful improviser with decades of experience he acquired on his own personal journey. The CL2 portray this complexity with ease and give each note its space. The insight and coherence are as good as it gets.

Zawinul Syndicate – World Tour

The album title “World Tour” cannot only be interpreted as a simple description of the nature of the recording – live concerts from a world tour, obviously – but also as a summary of its musical content. To this day, and 11 years after his death, Josef Zawinuls music is maybe the best example of what can be called “world music”. Loaded with complex rhythms and captivating melodies, calling this album “groovy” would be a silly understatement. This is the kind of music that happens when artists of the highest caliber from all over the world get together, led by a genius musician and composer, to make music that is beyond categories. The CL2s were able to deliver all the joy and passion that is on this album. From the first track on, it’s a sound that makes you move and enjoy yourself with its powerful drive. Later, on tracks like “Success” - what an extremely realistic presentation of church bells! – or “Sunday Morning / Sunday Evening” with its gorgeous synthesizers and passionate vocals, “World Tour” becomes an outright spiritual experience. The CL2s did not falter even a bit. They allow a clear, broad window into the music, being so carefully voiced as to never distract from it. I’m deeply impressed.

Deeper down the rabbit hole...

When I was thinking about how I wanted to approach this review, I was afraid that the reader might find it it not informative enough. The main reason being that I do not have a lot of audio gear that works with the CL2. At first, all I could offer was a detailed description of how it sounds with the iBasso DX150. Luckily, I soon realized that I actually have another option available, and that is connecting the CL2s to my standalone DAC, a version of the DDDAC1794 (have a look at my profile for more information about the configuration),via the Corda Jazz headphone amplifier. While not absolute top of the line, we are now talking about switching from a – very good – 500€ portable source to a 2000€ NOS DAC and a 345€ solid state headphone amplifier with switchable crossfeed. As I see it, it’s safe to say that this is certainly not a weak setup. Cables were a pair of Sommer Cable “Epilogue” RCA interconnects. Due to the how the Corda Jazz is built, I had to use the standard 3.5mm copper cable - plugged into a 6.3mm adapter - for the CL2s.

With the “big” DAC and the Corda Jazz, the CL2s sounded bigger and bolder in almost every aspect. Bass was now remarkably authoritative, with a strong grip, while I could listen into the most minute details of the music. Chords were wonderfully rich, with individual notes colliding with each other in colourful layers and textures. My head seemed to be enveloped in sound. Electrostat-like clarity but with more flesh on the bones, to sum it up in a few words. I honestly enjoyed every moment.

The CL2s are already very convincing driven by the DX150, but with the DDDAC and the Corda they clearly played in a different league. I realized that these IEMs are worthy of excellent companions, even if they cost considerably more. To put it in other words, in my opinion they are a realistic option for a high-end desktop setup.

Listening sessions: summary

The CL2s are faultless. I do not mean “absolutely perfect in every objective way”, but faultless in the sense that I have not discovered any issues with the sound. The sound is detailed, rich, tangible, wide, deep… whatever audiophiles usually look for. It’s so good that I genuinely don’t care about better options. The CL2s tick all boxes.

BONUS: PCM and DSD comparison

Given that the DX150 is able to play both PCM and DSD natively and the CL2 are so resolving, at some point I got intrigued by the idea to do a comparison of both formats. For that purpose, I downloaded two free tracks from the “test bench” of 2L (http://www.2l.no/hires/index.html?), namely “Et Misericordia” of Arnesens “Magnificat” in 24bit / 192khz PCM and DSD128, and a piano solo arrangement of “Ubi Caritas” by Ola Gjeilo in 24bit / 192kz PCM and DSD64. The latter is not available in a higher DSD format.

2L records in DXD, which means 24bit / 352.8khz PCM, and “cuts” all other formats from the original DXD file. As it is PCM, it can be assumed that the different PCM resolutions available through the test bench are closest to the original recording, with 24bit 352.8khz being, I suppose, identical to it. Nonetheless, I found it interesting to see if DSD sounds any different from PCM at all with the DX150 + CL2 setup. So I carried out a blind test in "abx" stlye.

I found no difference whatsoever. With my current listening abilities, using the DX150, playing those two tracks from 2L, my guess did not differ from random chance. I simply couldn’t tell which file format was playing during the blind test. This result does not mean that there is no difference in sound quality between PCM and DSD at all, as people with different gear and/or different ears could be able to reliably distinguish both formats. At the time of this review, both are equal to me.

Look and feel

The CL2s have a small form factor. RHA uses zirconium as the shell or housing material, resulting in an IEM that is durable and lightweight. My (cheap) kitchen scale tells me that each IEM only weighs around 8-10g, while touching them feels as if they had been made out of stone. This sensation, combined with the smooth, glossy surface reminds me quite a lot of obsidian (“volcano glass”).

The CL2s aestethic design can be described as sober and straight forward. In my eyes, it’s actually pretty timeless. I can imagine these IEMs to look just as good in many, many years as they do now. RHA cleverly avoided any current trends and designed an IEM that is not an eye-catcher by itself, but one that goes well with basically every outfit and style.


The Cl2s are deep-insertion IEMs. I probably got lucky, as the tips that are on them when you first open the box proved to be also pretty ideal for my ears. So I never had to go through much trouble to find the right tips, but my case is quite a rarity. RHA includes a nice array of tips and most customers will probably be satisfied with this selection. If not, there are many third-party options available on the market that will absolutely not break your budget. A good, tight seal is essential for every IEM and on the CL2s it greatly affects the low frequency performance. So take your time and try out different configurations until you are satisfied, otherwise you are definitely not going to hear what the CL2s really can do.


I have just realized that I completely forgot about bluetooth. I must admit that I am not very interested in it, but since the CL2 comes with a bluetooth option, I might edit in a paragraph about it soon.

A quick look tells you right away that the stock cables are certainly not cheap. For an IEM, both cables – copper for the 3.5mm plug and silver-plated copper for the 2.5mm balanced connection – have a seriously thick diameter, about 2.5mm for each channel. Many full-sized headphones do not come with cables that are as “hefty” as those of the CL2. While they are chunky, they do not tangle much and feel nice to the touch. RHA also did not opt for a simple memory wire, instead both cables have a – I believe more reliable - “memory spring” on each individual left and right end of the cables. In summary I consider these to be excellent stock cables, and so far I have not had a single thought of buying any aftermarket cables. It also means that this review does not discuss any other type of cable than the two that come with the CL2s.

Stock cable comparison

For the purpose of a comparison between the two stock cables, I attentively listened to Cherry Pie by Sade (from Diamond Life) and First Light / East River by Kenny Werner (from New York – Love Songs), both 44.1khz/16bit flac rips of the original CD albums. The Amp 6 module of the iBasso DX150 allowed me to use the exact same source for both cables.

To my ears, there is a small difference between both cables. Because of the absence of other cables with MMCX connectors in my collection, I cannot tell whether it is due to the different materials or the way how the CL2 is driven by the DX 150 depending on the output (not counting the decibel difference, which is simply a matter of adjusting the volume by 12 steps, as 12x0.5db equals 6db, the standard offset between single ended and balanced outputs on most gear).
With the copper cable, highs are a tad smoother and bass feels slightly looser, resulting in a sound that seems just a little bit mellow – which can be a good thing depending on your musical taste. In all other aspects I cannot detect any noteworthy changes. The CL2s still sound excellent with the copper cable and I find the presentation just as enjoyable as with the balanced cable. I don’t think that one can effectively change the whole sound signature by switching stock cables, but it is possible to tune the sound slightly.

What might seem a disappointing realization at first is actually a compliment to the engineers at RHA, who managed to give the same excellent sound to every customer, regardless of output options. Users who do not have a 2.5mm balanced output available don't really miss out on anything, and that’s how it should be.

Cable update, december 2018 (copied from the CL2 introduction thread)

Since the original publication of this review I have done a comparison between the Null Audio Vitesse (8 wires of OCC cryo copper, with upgraded mmcx connectors and 3.5mm plug), the stock copper cable and the stock silver-plated copper cable using my iBasso DX150.

The bottom-line result, ranked by sound quality from best to worst: Null Audio Vitesse > stock silver-plated copper > stock copper

Audio material:
"I.G.Y." by Donald Fagen, from "The Nightfly" album, and - as we are in mid-december- "Merry Christmas Mr. Lawrence" by Ryuichi Sakamoto, from the "Three" album. All 44.1khz / 16 bit flac CD rips from my collection.

Some notes on each cable:

The stock copper cable is kind of "easy" on the ears, it's got a nice voicing but sounds also a bit dull, veiled and muddy. Bass has the least impact and there's a lack of overall detail. It performs best in the lower mids, piano chords hit with a good amount of weight.
The silver-plated copper cable is much closer to the Vitesse in detail retrieval and articulation. There's clearly more power in the low frequencies compared to the stock copper cable. It's slightly bright in general and sounds exciting at first, but becomes a bit fatiguing over time.
The Vitesse is clearly the best cable out of the three. It sounds like a superior cross-breed between the stock copper cable and its silver-plated sibling: it's just as comforting as the copper and as detailed and exciting as the silver-plated cable, but without the imprecisions and lack of involvement of the former or the annoying sharpness of the latter. It's imaging is bigger and more accurate than what both of the stock cables can deliver, and it brings out great overtones and articulation in all instruments. It's also more comfortable around the ears and more flexible, so it's the obvious winner in this comparison.

Generally speaking, the stock cables are not bad though. None of what I have written in this update should lead you to believe that the CL2 is horrible with them on and I still think that RHA did a good job in that regard. It's just that the CL2 is so damn revealing that it can improve considerably with better cables.


I had a lot of fun writing this review. Sometimes, even as an amateur reviewer, after a while you risk losing interest in what you are actually reviewing. With the RHA CL2, the opposite took place as I was more and more convinced of their qualities.
The CL2s are a potential modern classic to me. Now, I realize what a bold statement that is, but their clever aesthetic design and excellent sound at a below 1.000€ price point make them attractive to many customers - while being a serious threat to the competition.
When I preordered my pair of CL2s, I was ready for everything. For me, it wouldn’t have been the first time that being an early adopter actually means “early disappointment”. Not this time though.

RHA hit the bulls eye.

I will keep my pair of CL2 for a long time. In fact, I am now seriously thinking about building a high-end desktop system around them. Here on Head-Fi, we like to answer such statements with “sorry for your wallet”. I believe the CL2s are worth it.


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I enjoyed this review mate. I like the way you have taken time to really define your meaning eg "faultless" and taken some time to talk about your process. I think i will be taking a leaf out of your book for my next review :)
This review is spot on, no hyperbole of any sort.
This IEM is that good, and thankfully AmanAnd88Keys was kind enough to take the time to answer all the questions I had about this planar in ear monitor, and convinced me to get them.
I have been listening to the CL2 for the last 2 weeks, and am having a hard time putting them down.
Thank you for taking the time to review these :)
love your review!! I wish every reviewer would show a pic with the Iem placed on the ear as you did. Have to save some money to grab this beast