Headfonics 2017

RHA CL1 Review


Low Efficiency

The CL1 is rated at 150 ohms and 89dB. Two immediate points come out of that spec. The first is that yes it genuinely does need an amp to prosper and sound at its best and second, the noise floor should be very low indeed on most of those amps and well-powered DAPs.

You should not be hearing any background hiss with the CL1. Consequently, weak amps from smartphones are not ideal for driving the CL1 optimally though you can get decent volume levels on some.

Low Background Noise

That being said DAPs and smartphones will give you decent results volume-wise and you shouldn’t expect a good DAP in high gain to have any driving issues and a smartphone to tap out volume-wise before it hits full volume.

Those DAPs prone to hiss on some IEMs like the FiiO X5iii will be totally silent when paired with the CL1 though expect much higher than normal gain and volume levels.


The “audiophile” ZTE Axon 7 smartphone with its AKM AK4490 DAC and reasonable amp out will take it plenty loud as well my Blackberry Passport but in the process, the low-end power is lacking in definition and the dynamics and contrast throughout becomes somewhat flatter compared to a good portable amp.

You do not get that same level of clarity and detail on a smartphone that a good amp can deliver.

The same also can be said of Apple devices with the 6th Gen iTouch tapping out volume-wise at 7.5 – 8 out of 10 but giving me a slightly drier sound than the Axon 7 as well as lacking in dynamics but slightly superior in its bass response.

Ironically underpowered devices such as the iTouch and Axon 7 produced a treble that’s still forward but for some reason less obtrusive with offending genres such as pop and rock than I found on better amps. That lack of power may have benefits for treble-sensitive smartphone users who want to use the CL1 for casual listening.


Tonal Pairings

Ideal 3rd Party Pairings

Again, this is about synergy and optimal driving conditions. You do not need a desktop amp to drive these but a quality amp and a reference or warm to musical DAC chip setup will get the right blend.

I found amps such as analog amps such as the ALo Audio V5 and the iBasso PB3 to be rather more enticing blends for the CL1 using smartphone transports and the likes of the Chord Mojo and the Continental Dual Mono for all in one DAC/Amp solutions where the focus is on musicality and that tube warmth from the CDM.

Solid performing DAPs for tonal pairings include the AK380’s slightly warm but very detailed signature, the mid-range, and musical FiiO X5iii, and the liquid-like Shozy Alien Gold edition.

Mix and Match Possibilities

You can still work a neutral DAC in with the CL1 but this will entirely depend on your choice of tracks. Any music with a focus on percussion attack or a bright recording is going to come off a bit too hot with the CL1.

If it has energy beyond 2k and is hitting you with a wall of it already in neutral to warm IEM’s it won’t come off good on the CL1 with a neutral DAC/amp combo unless you EQ it heavily.


Of course, RHA really wants you to get the Dacamp L1 to pair with the CL1 for obvious reasons. First, it is referenced with the CL1 in mind right from the start and the second is you can actually deploy the spare balanced silver core Ag4x balanced cable with 4pin Mini XLR termination with comes in the box.

You really cannot use the cable with any other IEM or portable amp that I know of without substantial re-termination on both ends.

Dacamp L1

Without getting into too much detail the Dacamp L1 is a dual Es9018K2M DAC feeding into a Class AB amp and outputting into either a single unbalanced 3.5mm output with line-out as well as a single mini-XLR balanced output.

It has got decent power with a max output of 300mW into 16 ohms, 10 hours of battery life as well as gain, bass, and treble hardware EQ options. Its 11dB SNR is not earth-shattering, I see more sensitive amps at lower prices up to 120dB with the iBasso PB3 and 115dB with the A5 but the THD numbers are excellent at >0.0018%.

It’s a fairly neutral but driving amp with an emphasis on detail (Sabre DAC’s forte) and in some ways reminds me a little of the Mjolnir MK1 with its lively but resolving amp signature.

The ability to tune the bass and treble via their dial-based hardware EQ system on the side is nothing unique but it really does help extend the matchability of the CL1 pairing if you find the bass or treble a bit too much. The low gain setting for the CL1 using the Dacamp L1 is more than fine by the way for most everything.

Unbalanced/Dacamp L1

Studied Selection

In unbalanced mode with the braided OFC cable, the CL1 is fussy in terms of genre selection when paired with the L1 and is more top-end down than bottom-up in terms of tonal presentation. Clarity is excellent (particularly at low volume) however and paired with acoustical work, sparse tracks, and contralto vocals the control is excellent.

Treble Balance

Treble on this pairing is still somewhat edgy. the old adage of garbage in, garbage out is somewhat true but even more so with any recording that still pushes a heavy emphasis on percussive attacks. The lower treble energy should be handled with care and with just the right amount of energy it sounds very impressive.

Stick on some hi-res Christine Winn, early Dire Straits, or 70’s Billy Joel and you will get a fantastic range and articulation from the CL1. Throw in the busier Metallica, Maiden, or even Ellie Goulding with that piercing vibrato vocal range and it suddenly can get a bit too hot.

Dacamp EQ

If you want to tweak the CL1 sound a little the L1 bass and treble EQ is actually very useful. The L1 treble can be taken down just enough to dampen anything you find too sharp yet keep its edge and detail firmly to the front.

It is something I find to be using a lot for riskier track selections and at times it can amount to a much easier listening session. I would advise using the bass boost combined with a treble decrease with the CL1. It sounds a bit overly bloated and lacking in contrast as a result. Best to simply dampen the treble to -2 and keep the bass at zero for the best compromise.


Balanced/Dacamp L1

This is the money shot for me, the best of all the matches with the CL1 and a step up from the unbalanced output of the Dacamp L1. I really get a feeling that the CL1 is getting some decent power and running at optimal levels.

This means a smoother attack, a shorter decay, and a more natural lower treble performance than the unbalanced output. With the right track playlist, I could actually listen to this pairing all night. Line up some Cocteau Twins, Straits, Pink Floyd, and Fiona Joy and I am right at home.

It’s still elevated and forward though so do not expect syrupy good times but this time it feels more coherent without the additional hardware EQ required and generally lends itself a bit more to a wider selection of genres.

I would love to have seen how that pure copper cable in balanced mode could have performed as an alternative because all the qualities of a good silver cable are shining through – tight, precise, and clean.

Select Comparisons




The IE800 is a 16 ohm 125dB single DD IEM and it the flagship IEM for Sennheiser. In price terms, yes, it’s a bit more expensive than the RHA CL1, it is also easier to drive than the CL1 but it is a horrible fit, offers clunky proprietary tips and a cable from hell.

Physically it is not the full shilling compared to the superior detachable cable and smooth well-fitting ceramic housing of the CL1. Detachable tips and cables make the CL1 a more durable proposition at least on a physical level.


If anything the tonal presentation of the CL1 seems inspired by the IE800. Both have relatively similar response curves with elevated low ends, recessed mids, and ethereal and somewhat edgy treble performances.

However, side by side the CL1 is the brighter of the two and its midrange energy starts a little earlier than the IE800 at around 2k whereas the IE800 energy starts closer to 4k. This has the effect of giving more prominence to alto and soprano vocals on the CL1 than on the IE800 which will sound more recessed in comparison.

Treble on the IE800 though is a little less peaky and bright with its focus closer to 10k than 5-8k on the CL1 but it is known comparatively speaking as a bit brittle and thin at times.

So whilst neither are relaxing top ends both have an airy sound with the IE800 being the more flexible for lower treble performance across a wider range of genres. The gap though is less clear with the CL1 in balanced mode.

Campfire Audio Lyra II



The Lyra II is a 17-ohm 102dB single beryllium DD IEM from Campfire Audio and comes loaded with a PVD finish on a liquid metal alloy housing, a really nice Litz cable, and some good accessories.

Interestingly the Lyra I was also a ceramic housing built using the same materials as the CL1. It is far easier to drive though than the CL1 though doesn’t scale quite as well as the CL1 can with a good amp.


Tonally these two are quite far apart. This is a warmer more musical offering with a more prominent midrange and a more laid-back treble. Bass is texture and full sounding but not as elevated as the Cl1. It doesn’t have the same upfront impact but instead has a greater emphasis on sub-bass with a slightly loose sound than the Cl1 bass response.

Timbre is more euphonic, rich, and thick sounding than the more clinical and precise nature of the CL1. Vocals are also more prominent on the Lyra II with less sibilance.

Treble is clean but relaxed sounding losing out to the superior headroom and airy feel of the CL1. The Lyra II is really suited to mid-focused rock and pop and doesn’t have the imaging and staging depth and height of the CL1.

The CL1 may have the greater potential of the two in terms of scaling capability but it has the more immediate and forgiving sound. Two very different tonal presentations I suspect for two very different moods.

Sony EX1000

$300-400 (discontinued)


The Sony EX1000 is a 32 ohm 108dB single DD IEM sadly now discontinued but has retained a respected following nevertheless. Physically it’s more in the IE800 camp regarding shape and fit with its unusual angular fit preventing a truly deep seal and top-notch isolation.

Ironically though it is comfortable once you get the right seal and isolation is pretty good but not to the level of the CL1 with foams though superior to the IE800. It is also much easier to drive than the CL1 but neither offers any issues when it comes to noise levels on DAPs and most portable amps.


Tonally the EX1000 is still a classic for me and still very competitive 7 years later and also in some ways shares a lot of similarities to the CL1.

For one they both have edgy treble that some would consider bright though the CL1 would take that tag and then some contextually speaking in unbalanced mode. Once again, the situation becomes much more competitive when the CL1 is balanced with more control and body as well as sounding airier.

The Sony also has a bit more body than the CL1, particularly in the lower midrange where instead of a dip you have a gradual rise from a more linear and balanced bass response. To the credit of the EX1000, there is significantly more 1-2k energy than the CL1 provides giving a welcome boost to male vocals.

If you want a bit more substance and impact in your bass performance the Sony does well but it’s a bit soft in comparison to the CL1 more substantial weight. Imaging on the CL1 is superior to the EX1000. Though it has a pleasing presentation with plenty of ambiance the spatial cues and instrumental positioning is a bit more vague sounding than the CL1 more nimble performance.


Our Verdict

I have to congratulate RHA first of all for taking a risk with the CL1. I can’t say for sure this will be a signature sound for the team but it is certainly a departure from the likes of the T10 and T20 and in many ways, it’s a deeper experience, a long journey fraught with challenges but when it clicks this is an incredibly immersive IEM with top-notch detail.

It also the most expansive package I have seen for a while for an IEM in this price range. The inclusion of not one but two very high-quality cables is very commendable, even if the connectors are proprietary and the balanced version really does need the Dacamp L1 to be considered relevant. The tip selection is fantastic, the build quality is excellent and the case is durable as always from RHA.

Matching makes the CL1 tick and will ultimately determine whether you like it or not. Not just amps, but sources and ultimately the type of music you prefer. When the match is just right the CL1 is detailed, articulate, and vivid. When you get it wrong then yup in comes the anti-marmite crowd EQ’ing that treble down a few notches.

I get that. This IEM is not for everyone yet sometimes pinning your colors to a particular coloration of sound may yield a smaller audience but you can be pretty sure they will be fervently into the sound a bit more. A cult hit? The Dune of the audio world? Very much a possibility.

RHA CL1 Technical Specifications

  • Driver Type: Dynamic + ultra wide band ceramic (CL) driver
  • Frequency Range: 16 – 45,000Hz
  • Impedance: 150 ohms
  • Sensitivity: 89 dB
  • Jack: 3.5mm gold plated – straight (SE) mini XLR gold plated – balanced
  • Cables: Braided OFC (sMMCX-3.5mm), Ag4x (sMMCX-Mini XLR)
  • Weight: 14g (without cables)

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