k.e. 2017

NF Audio NF6i Review

Disclaimer: The NF Audio NF6i sent to us is a sample in exchange for our honest opinion in this review. We thank the team at NF Audio for giving us this opportunity.

To read more about CIEM products we reviewed on Headfonics click here.

Note, this 2-page review follows our new scoring guidelines for 2020 which you can read up on here.

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6.499 CNY (~ 940 USD, 890 EUR)

NF Audio might not ring a bell yet. As of now, Chinese CIEM brands are not quite popular in the international hifi scene. But NF is hoping to change all that.

宁梵 Ning Fan is the first Chinese CIEM manufacturer to trigger my interest. The company was only founded in 2014 and is based in Shenzhen, close to Hong Kong’s border.

In addition, NF stands for Near Field (monitor), Nice Fit (and perfect isolation), as well as Nice Frequency (response). It essentially encompasses the term CIEM with custom-fit and precise audio for monitoring capabilities.

What’s the Pitch?

I received a note from a Chinese hifi friend who read some amazing impressions of the NF6 monitor online. Apparently, some people were of the impression that the NF6 is the single best audio experience, being only challenged by legendary electrostatic headphones from Stax. We surely do not want to miss the hype!

Though I was not fully convinced by the article, it did motivate me enough to track down a contact around some detours after I realized that the official contact email on their website is outdated.

Please do note that while I officially speak, read and write Chinese (after studies and a year abroad), my Chinese is still limited and I am especially not familiar with the hifi vocabulary outside the textbook. Thus, communication with NF Audio was not easy and I cannot guarantee that there are no translation errors or that all information about development and company history are 100% correct.


Putting the spots on the NF6, we are looking at a six-driver monitor with a 4-way crossover. The trump card is a proprietary high-frequency receiver that is supposed to push the performance above the competition.

However, many first impressions hinted that specifically, the NF6 monitors were extremely difficult to drive. By the time my ear impressions reached the other end of the world, NF Audio already improved on the original design and introduced the NF6i, basically the same earphones with higher sensitivity.

Order Process

Review units sometimes go past normal standard ordering procedures. This was also the case with my review unit. I did not choose design options myself. My aim is to assess the sound and build quality.

If you are interested in the design options, I suggest visiting their official homepage at www.nfaudio.cn and head straight to the gallery. I found an extensive selection of woods, laser artworks, color prints, carbon, glitter, and metal artwork. Judging from the pictures, the selection is very reminiscent of Rhines Customs, Vision Ears, and Jomo Audio.

Placing Orders

The only way for non-Chinese to place orders right now is to visit the Chinese platform 淘宝 Taobao and go through the standard procedure. There are non-affiliated services that help non-native speakers without Chinese payment methods to follow through with an order, but I don’t feel comfortable enough to recommend one.

I am not sure how experienced the company is with international shipments. When importing, passing the customs office could turn out to be a problem depending on your country. The CIEMs are not cleared with a CE-label (Communauté Européenne) so keep that in mind. In the worst possible case, the customs office could dispose of the package. Thus, I involved a local friend who helped me bring the earphones overseas. I recommend you do the same.

Future Plans

The company told me that they are working on expanding above international borders and expecting universals down the line is not a wild guess. However, there is nothing precise I can promise at this point. A universal version of the NF6i might or might not happen. This monitor is also not their newest version. A makeover of the NF4 is currently the CIEM with the most attention within the company’s lineup.

The Final Product


My customs have a deep purple color with a hint of glitter and a swirl on the faceplate. It reminds me of Psychedelic Rock covers from the nineties. I can surely dig that! The logo is humbly placed into the corner. I have to admit, I was expecting some more bling from China. I am surprised by the earphone’s modesty.

The color allows some insights when held against the light, however, it is quite opaque overall.


The NF6(i) earphones are built in a 4-way crossover with six drivers. Surprisingly, NF Audio does not rely entirely on largely available drivers by Knowles and Sonion. They have created a unique and proprietary driver for high frequencies that is supposed to help the brand surpass the competition. The NF6i is easier to drive than the NF6, which is said to be very picky with source amps.


Looking down inside the nozzle, you can see a 3-bore design. Each bore ends with a silicone tube and they come together in a hollow chamber before entering the ear canal. The very tip and inside of the nozzle are not as polished as the outside. Some lacquer hardened in shapes that always make me believe I made them dirty with ear wax. It’s not an issue but also not the prettiest polish.


The outside part of the CIEM are brushed up nicely, however. The transition from shell to the faceplate is not noticeable. The cable connection is not recessed. The overall build quality is very solid and not far behind the likes of Jomo Audio or Vision Ears.

A serial number is laser-engraved on the top outer space on one side only. I would have been the 4th owner of the revised NF6i if I had the logistics figured out better.

Fit and Comfort

I have no issues with comfort. However, the CIEM are not very tight. I can deliberately break the seal if I want to. Compared to my other customs, these are the easiest to insert and to remove. While I find this especially comfortable when laying in bed or working at the desktop, I would not want to jump on stage as an artist with these. In that case, I would ask for a refit and a tighter fit.

Packaging & Accessories

The accessories are fairly standard. An unbranded Peli 1010 case, a cleaning tool, and a warranty proof of purchase card. The earphones have the standard Plastics1 cable already attached.

Less usual is the beautiful and sturdy cardboard box with NF branding. This adds a premium feel that many CIEM manufacturers are lacking. I did not find a manual in my box. There should be one included, but it is only in Chinese anyway.

Sound Impressions

Tuning, Pt. 1

At first listen, the NF6 really had me fooled. For the first three songs, I was of the impression that the tuning is neutral and flat across the board. But that it is not. However, bass, mids and highs are almost equally present. NF-Audio created an extremely poisonous and addicting W-shape as opposed to general popular V-shapes.


The NF6i features a very lively bottom end. Bass extension reaches very low and allows slam in electronic music or necessary atmospheric rumble in Orchestral soundtracks. Yet the bass does not come off as pronounced.

The accentuation focuses on the sub-bass allowing an almost dynamic-y body. Luckily, we are still in the balanced armature-range and the tightness is enjoyable even with fast Thrash Metal tracks. Warmth is comparably recessed, giving less texture than a neutral response but thus also allowing more musicality without drifting into the bassy territory.

The bass elevation is fairly moderate with peaking at around +6 to 7 dB. It is nothing that will woe bassheads but it is also very far from anemic. We are definitely in an era in which people appreciate a mild bass boost over the absurd bass quantities of last gen’s monitors. NF Audio follows recent trends and adds but a little oomph.


The midrange sounds very natural with a realistic body and high detail. The presentation from 250 Hz to 2.5 kHz follows the ideal response closely and allows great detail. There is a little bit added edge at around 3.5 kHz but the NF6 doesn’t sound too forward. Actually, the upper midrange takes a dive after 4 kHz up until the high frequencies from 6 kHz upwards.

The local minimum at around 5 kHz could be a phase issue but it could just as well be intended. I wouldn’t know. Anyway, it takes out any harshness from the midrange while hardly hurting the details. Instead, it allows for a more spheric soundstage. But more on that later.

In the big picture, voices still lack a wee bit of presence next to bass and treble. However, this is comparing with studio references only. It is not enough to cast a veil on male voices or to bleed warmth into the body. Electric guitars still have all their energy and neither male nor female voices sound tonally off.

Sadly, my unit is slightly unbalanced between left and right at around 1-2 kHz. That makes one side sound a very tiny bit tinny. It is not an issue that is easily noticed while music is playing, but for professionals that ask for perfection, it could cause some confusion. My ear canals are not symmetrical, however, so I don’t want to over-emphasize the 3 dB difference. (Remember, I also noticed a disparity with my Jomo CIEM in this area.)

High Frequencies

Let’s finally talk about the showstopper here. The high frequencies of the NF6i are absolutely addicting like nothing I have experienced in an IEM before. They are incredibly revealing with a ridiculous amount of detail and clarity.

Even though they are very present, they never sound sibilant or piercing. The amount of air and natural space NF Audio managed to reproduce is absolutely fascinating and it makes many earphones sound very compressed and dull in the treble.

In the introduction, I mentioned impressions comparing the NF6 with electrostatic earphones and now I can fully understand why. It doesn’t even sound like a CIEM anymore. I cannot even think of any closed supraaural dynamic headphone that manages to create such a convincing treble. Yes, I know that that is a bold statement but I stand by it.

Even though the high frequencies are smooth, should one absolutely detest present treble, one could argue that after prolonged use they could be perceived as hot. 9-14 kHz show a steady level that is very uncommon for balanced armatures – or almost any IEM for that matter. Even more impressive how NF Audio managed to maintain an overall smooth signature. This is a true improvement over the harsh treble peaks we had to accept some years ago.

Tuning, Pt. 2

After having the sound signature picked to pieces, I think it’s fair to make the description whole again and to take a second look at the overall tuning.

Despite not following a natural or neutral frequency response like Etymotic or the recent InEar ProPhile 8, the NF6i sound smooth and still manage to sound natural and musical.

The NF6i are not bright sounding earphones. Quantity-wise, bass, midrange, and high frequencies are well-balanced, yet every segmentation has its uniqueness that creates a more lively presentation on its own. The bass focuses more on the very low-end, the midrange has more crunch than the edge and finally, the treble shies away from sibilance but adds definition and air.

It feels like the NF6 has more of everything: more bass, more mids, and more high frequencies. I don’t know any other IEM that tries to achieve the same. The NF6(i) features a fun sound signature that has neither recessed mids nor sibilance and that makes it even more enjoyable to listen to as an all-rounder.

Soundstage, Imaging, and Resolution

The soundstage is very wide and has ample depth. The amount of air and definition from the treble helps greatly with separation and layering. A slight suction in the upper midrange/ lower treble pulls voices back maybe just one or two rows. This results in a spheric presentation with the listener sitting in the 4th or 5th row instead of standing in the very front like with the ER4.

I did notice that the imaging is not super precise. Some instruments tend to drift vertically. Especially drums sometimes sounded like they were below in front of me and cymbals hit over my head instead of being on the same height. I used Dr. Chesky’s binaural test tracks for a more detailed analysis, but with such reference material, the issue was hardly noticeable.

Treble can carry a lot of information. And in this case, it not only provides great separation and layering, but also amazing clarity. I am trying my best to stay away from the term ‘transparent’, but I know many reviewers would be throwing this around right now. However, the NF6i are not transparent as they have a uniqueness to their sound, somewhat floaty and easy, but they reveal a crazy amount of detail. Even though the bass is tight, the focus lies with mids, treble, and their partial overtones.



Despite my review unit being the revised NF6i instead of the original NF6, they are still somewhat power hungry when compared to other multi-BA designs in the same league.

For example, hooking the ifi iEMatch up to an iPhone 6S Plus, it is very likely that you will hit the max volume cap on ultra. An even less audiophile device like the Nintendo Switch might not provide enough volume for your needs altogether. The sensitivity is rated at 106 dB. A full-size orthodynamic like the Oppo PM3 can even achieve higher volumes.

Hugo Pairing

However, the NF6i are not so dependent on the output impedance and they do not tend to pick up hiss easily. Naturally, the Chord Hugo is a great source yet again. This chain creates an ultra-lightweight feel with the music just floating in front and around you. The experience is close to mesmerizing.

Mojo Pairing

The Mojo adds some deeper blacks but takes away some of the magical space in the treble. Going straight to the iPhone 6S output, the NF6i play more forward with heavier and slower bass. The treble luckily doesn’t lose precision, though. My desktop reference RME ADI-2 Pro is fully transparent and got the most natural presentation out of the NF6i. Neither bassy, nor forward but with a realistic treble.

Select Comparisons

Campfire Audio Andromeda

You cannot mention clarity in a review and disregard the reigning popularity king Andromeda by Campfire Andromeda. Based on other user’s reviews, I was expecting the Andromeda to sound similar.

However, having already adjusted to the NF6i for a few weeks, the Andromeda left me very underwhelmed. Andromeda’s midrange appeared not only strongly recessed, but voices were a bit muffled in an A/B-test.

More noticeably, the Andromeda showed minor sibilance issues – something the NF6i does not have and yet still provides more clarity, more amount of treble, and much more air. The Andromeda also sound thicker as they have more bottom-ground.

These are two different signatures with the Andromeda being a warm-bassy monitor with some balanced treble energy. I have to admit that I prefer the more lightweight sound from the NF6i that also features punchy bass and lively treble yet shows less fatigue and a more natural midrange.

Once you get used to the warmth, the Andromeda do have great coherency and better imaging, but switching back to the NF6 is like surfacing from under the water and gasping for air.

Jomo 6 V2

My pair of Jomo6 V2’s are masters of bass texture and they provide string details on cellos that the NF6 cannot render. The 6V2 sub-bass tightness is still amazing. The transition from bass to mids is also more natural and the midrange is more behaved.

However, voices sound more alive through the NF6 because of the middle W-signature peak. While signatures can be a preference, I do have to rate the treble performance by NF Audio as much better. The Jomo sound compressed in the treble and lacks the air and realistic shimmer of the NF6i.

InEar ProPhile 8

As for natural-sounding monitors, the InEar ProPhile 8 are hard to beat at the moment. When put up in an 1on1, the NF6i firstly showed that voices appear a little more distant due to the upper midrange drain.

Instead, they put maracas and other high frequent instruments more to the front. But not too much, the timbre remains natural and convincing, even if a little bit fuzzy when challenged by the ProPhile in subpar recordings. Both monitors render male voices well and relaxed. The PP8 are more transparent with female voices, though, which appear a little bit warmer on the NF6.

Bass and dark wood instruments sound amazing on both monitors. The overall bass quantity of the NF6i is more comparable to the PP8 with activated bass boost, but the InEar will show more slam and greater impact than the NF Audio. (This is likely due to comparing a CIEM with a universal.) Surprisingly, the NF6 has a wider and deeper soundstage while boasting equally impressive layering and separation.

In the end, the ProPhile remain a bit more transparent (especially in the lower treble) with similar clarity, flat frequency response, having superior driver matching, and thus are more suitable for monitoring.

However, the NF6 features great performance and provide a bit more fun-factor even when the ProPhile has both switches activated. Having minor issues with coherency and transparency, after prolonged use, NF Audio anyway just landed on the number two spot on the list of my favorite IEMs.

Our Verdict

NF Audio caught me by surprise. Based on Chinese local reviews, I was already expecting a solid contender with an enjoyable sound.

Obviously, one would expect a newcomer brand to punch the price very low. NF Audio did all that, but that is not even enough to describe the NF6i. This earphone is unique and just as enjoyable as many well-regarded TOTL CIEMs.

The high frequencies performance is outstanding. The clarity matches that of an open vented design yet allows high isolation in a custom fit. All without fatigue or sibilance. The NF6i sound fresh and have a unique selling point.

The NF6i are not a new studio reference as their W-signature does not allow the most precise of monitoring across the frequency spectrum. The accurate mid-range floats like an island between the present sub-bass and airy upper range.

Overall, the NF6 are refined all-rounders that do not let any detail go amiss with any genre. It’s all there, plenty and balanced. They sound fun and hardly colored at the same time. They left me impressed.

Being able to place an order through a Chinese market only will understandably be a huge turn-off for most. But this is a product I advise to put on the watch-list. International dealers or a universal fit might be on their way; at least I hope so, for a more competitive market.

Technical Specifications

  • System: 6 BA, 4-way design
  • Frequency response: 8-30 kHz
  • Impedance: 18 Ω@1kHz
  • Sensitivity: 106 dB@1kHz
  • Distortion: below 0.5 %
  • Isolation: 26 dB (CIEM)

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