Headfonics 2017

The CL750 By RHA



For Use With Amplifiers

The CL750 measures the same as the CL1 at 89dB and a whopping 150 ohms. This is the poster child for budget audiophile ratings in an IEM and “Made For iPod” it most definitely is not. In fact so glaringly inefficient there is actually a warning sticker on the front of the box in case you might have missed the implications of such a spec. The silver label simply reads “For Use With Amplifiers”.

The good news is however that the CL750 is pretty much a noise free experience on almost all sources and amps I threw at it including FiiO’s X5ii, Cayin i5, the DX200, ALO Audio’s RX IEM amp, FiiO A5 and RHA’s own impressive Dacamp L1. Even ALO Audio’s powerful and sweet sounding V5 portable tube amp is noise free with excellent channel balance when hooked to the CL750.

Cost Of Entry

Now, of course, you can stick the CL750 in some sort of souped up Smartphone and you will get a modicum of voltage to drive it at suitable volume levels but this will neither be optimal nor wholly enjoyable with a distinct lack of dynamics and an overly glassy treble. As an example the AK4490 driven ZET Axon 7 smartphone took the volume pretty much to the max and gave a really nice smooth sound, much like how the CL1 performed but with a degree less extension on the top end and a flatter bass response.

Your minimum ‘starter for 10’ should be a DAP with a decent quality amp or better yet a good quality external portable amp. Good DAPs such as the X5iii will cope in low gain with the CL750 sitting at around 95-105 in low gain for the DX200. Portable amps will increase the cost of entry to enjoy the CL750 somewhat but budget models such as the FiiO A5 will be more than enough power wise for around $120. Even the smaller A3 or Q1 will be superior to your smartphone’s performance without having to invest hundreds into a high-end DAP.

Tonal Pairings


The CL750 with foams seems tailor made for the smooth laid back tones of the X5iii or the more balanced and detailed but equally smooth X7 with the AM3 module (unbalanced output). You can get as good, if not better the higher up the DAP chain you go but the costs will provide a significant barrier.

FiiO X5iii


The X5iii pairing exhibits zero noise which is hardly surprising given the CL750 ratings and still has good voltage control and output power in low gain with volume sitting comfortably at 80-85 in low gain mode.


Tonally the X5iii adds a bit of thickness to the CL750 sound, with a full sounding midbass response and decent texture to vocals. Imaging is excellent and nuanced spatial cues are perceptible and clear. It won’t fatten out and pull down the lower treble spike but neither will it play havoc with the presentation.

This is a great pairing with subtle EDM with a hint of ambiance. Electronica acts such as Disclosure and their short and quick cymbal and clap attacks over an ambient chill background have excellent layering and clarity.


FiiO X7/AM3


A similar performance from the X7/AM3 in terms of noise control and voltage requirements with a volume setting around 85-95 in low gain and no background hiss.


Tonally this is a touch thinner sounding than the X5iii but more resolving and detailed with slightly better dynamics and a vocal performance that is more to the fore. I am in two minds about this pairing. Whilst I recognize the balanced performance, the excellent control and clarity I actually give the nod a bit more to the X5iii just for the better synergy with the CL750 in terms of PRaT and a slightly more musical and forgiving sound signature.

I think I can forego the detail and increased realism a little in favor of musicality at times when it comes to modern genres though I find myself switching to the X7 for acoustical work using the CL750 precisely for that detail.

iBasso DX200


Much like the FiiO DAPs, the DX200/CL750 pairing is noise free with no background hiss as well as having plenty of voltage for sufficient volume at low gain levels (100-110 steps approximately).


Tonally this is a fantastic reference pairing but I would not find that surprising given the price point of the DX200. With the latest Sabre ES9028 DAC, it has the resolution, control, and dynamics of the X7 but it sounds more refined. The CL750 lower treble still comes in focused and boosted but it’s smoother sounding with a slightly longer and more natural sounding decay that balances better with its brilliance performance.

Vocals stand back a little from the X7 signature, not quite as bright, slightly warm but natural sounding with the CL750. Bass is not as full sounding as the X5iii/CL750 combo but it tighter, quick paced and well defined. iBasso talk about this amp module as being reference sounding and in the case of the CL750 pairing, it seems to be very much the case.

Sony NW-A35


It doesn’t quite have the voltage output to really get on top of the CL750 in terms of volume control with all the EQ stuff switched off. For DSD, using the CL750 I was way up to almost max out and only started dropping down with the use of little EQ tweaks like the dynamic normalizer setting and ClearAudio+. Noise control, of course, is excellent.


Tonally this is the sweet spot between price and performance out of the DAPs tested. I would still grab the X5iii if I could but given the $140 MSRP of the CL750, the cheaper Sony A35 makes a lot of sense. You get a full sounding presentation and the slight reduction in voltage seems to do nice things with the lower treble which drops back a touch.

Vocals are ever so slightly sibilant though and the treble extension takes a bit of a bit but otherwise, this is a warm and very forgiving sounding presentation. Think Knopfler over Iron Maiden and you are in the right direction with this pairing.


In terms of value to performance, the FiiO A5 and iBasso PB3 were the ideal pairings with the CL750.

FiiO A5

Two things came into play also with the A5 and the CL750. The treble peak sounded more controlled with an amp signature such as the A5 which pulls back the treble forwardness a touch leaving plenty of sparkle but less heat and a more rounded response. This more rounded signature really gelled well with synth-laden tracks and more percussive infused rock where weaker amps tended to give a more brittle lower treble texture to the CL750.

The noise floor was very low also with the A5 with no perceptible background hiss and importantly I got decent voltage control in low gain with the A5 which other IEM’s sometimes fall a bit flat. Up to around noon or 1 pm in the pot position which is on the same level as some 32-ohm portable headphones.

iBasso PB3

I absolutely loved the PB3/CL750 pairing though for its more open sounding midrange than the A5. It does though have a slightly leaner and quicker paced bass response compared to the more substantial A5 low end but up to its lower treble it is smoother sounding with the CL750. Noise and background hiss performance on this pairing are also excellent and you do get a bit more pot control than you do with the A5 in low gain mode.

Lower treble on the PB3 is softer sounding than the A5 using the CL750 but with a slightly longer decay and a tiny bit of roll off in the very final octave. The even harmonics bias and open mids of the PB3 makes a very solid pairing with the clean and articulate u-shaped presentation of the CL750.

Select Comparisons

Brainwavz B200



Brainwavz have always done a nice job on retail packaging and the B200 is no different with a good selection of tips and a barrel zipped case but it pales in comparison to the stellar packaging of the CL750 which just that bit more for that bit less. Build wise the CL750 is of a much higher grade of material than the B200 plastic materials though the B200 is much smaller and lighter in the ear. Both seals well with Comply foam tips supplied.

The B200 is a dual BA IEM rated at 30 ohms and 110dB. It is vastly more efficient and easier to drive than the 89dB and 150-ohm rating of the CL750 though I would not term it as ultra-efficient. Like the CL750, it does a good job suppressing noise and background hiss, even on the portable tube V5 from ALO and does perform that bit better on a quality signal. Unlike the CL750, the B200 does not really need an external amp to be driven well though it does have some benefits tonally.


Tonally the B200 is a smooth balanced BA design with linear clean and typically BA bass performance, nice open and quick paced mids with a slightly forward vocal presence. Treble is clean, articulate but laid back and slightly rolled off. In comparison to the CL750, the B200 is a jack of all trades and a specialist of none and aimed squarely as a ‘beater’ with good sound.

In contrast, the CL750 has a warmer more emphasized mid-bass hump, thinner midrange with a more recessed lower midsection and a more energetic and very articulate top end. It beats the B200 in terms of presence at both extreme ends of the frequency response, has a more precise imaging quality and better staging all round.

It would be fair to say the CL750 is the cleaner of the two and more of a specialist tool that’s really great at one or two things than just good at many things. As such its much easier to pick up and go with the B200 but for a more immersive experience with the right match the CL750 will offer more.

AAW Nebula One


The Nebula One is a 16-ohm and 100dB SPL rated single DD from AAW. The 10mm DD is an ultra-thin layer titanium diaphragm with Neodymium drivers encased in a stainless steel housing and pitched at mobile phone and DAP users with inline mic and remote control. The price is competitive though the packaging and presentation a shade lower than the CL750 which really has no equal at this price point.

Efficiency wise the Nebula One is the easier of the two to drive by a considerable margin and has no need of an external amp to be driven properly. That being said it is not super efficient and will avoid showing up hiss on higher noise floors.

Tonally the big difference between the two is the lack of top end extension and air from the Nebula One in comparison to the more forward, cleaner and more articulate CL750 top end. The extension on the CL750 top end is vastly superior. Detail is good on the Nebula One but it doesn’t have the same level of clarity and instrumental separation as the CL750 which is very controlled in comparison. Vocals on the Nebula One are more forward sounding than the CL750 and its low end is thicker and more dominant in its sub-bass performance compared to the more rolled off CL750’s sub-end response and warmer mid-bass boosting.

Echobox Finder X1



This is a really close match up right across the board. Solid titanium steel versus 301f stainless steel teardrop shells, unique single dynamic drivers, beautiful accessories, and tips tray/case and a similar price to boot. The only key difference is the Finder X1 triple filter system which does add a bit of value but if you like only one then its neck and neck.

The CL750 for me does have a slightly better cable and jack feels more solid and better weighted though the Finder X1 does come with remote control playback and mic and is “Made For iPod” with a 22-ohm 96dB rating. It is not a hugely sensitive IEM though more so than the CL750 and does not require amping really to sound at its best. Like the CL750 it will successfully navigate and avoid hiss in most portable setups.


Tonally both have similar setups with u/v-shaped frequency response, a warmish low end, recessed midrange and sparkling treble performance. The key differences are a more weighted sub-bass to mid-bass response in the X1 compared to the mid-bass elevation of the CL750 and a more rolled off or subdued sub-bass signature. Mids on both are dipped but the CL750 has a slightly fuller sound than the X1 and a smoother vocal performance. Both have excellent control and clarity but I again give the CL750 the slight edge in imaging.

Both have forward and dominant treble ranges but the X1 has a dip in the upper mid to lower treble and a higher peak at 8k compared to the boosted CL750 lower treble which is sustained and more energetic into its upper treble. You get a better extension, more clarity and perceived detail from the CL750 but you get a slightly smoother treble from the X1 which might be more tolerable to treble heads, especially with the bass filter.

Our Verdict

It is very tempting to call the CL750 a baby CL1 and in many ways, it does mimic its more expensive sibling albeit not quite at the CL1 level, especially for low-end impact and top end extension but it’s close.

At $149 that makes the CL750 a bit of a bargain if you enjoy that bright clean articulate sound. Imaging is particularly good on the CL750 though again some studied matching does some wonders overall. Warm and smooth DAPs seem to be the best match and whilst it will not change up the signature significantly the injection of warmth does give it a bit more in terms of genre flexibility.

Throw in an excellent retail package, a top notch selection of accessories, a quality cable and a shared DD driver from the CL1 and there you have another potential win for RHA at the budget level.

Technical Specifications

  • Connection: Stereo 3.5mm
  • Frequency Range:,16Hz-45kHz
  • Impedance: 150 ohms
  • Sensitivity: 89db
  • Phone Controls: No
  • Removable Cable: No
  • Type: In-Canal
  • Weight: 39g

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