NF AUDIO NA1

NF Audio NA1 Dynamic Driver IEM

Based on the documentation included in the package, Shenzhen Ningfan Acoustics Co., Ltd. manufactured this product under the NF Audio brand name. They also noted that the NF stands for “Near Field, Nice Fit, Nice Frequency.” The brand has released several other earphones already including custom fit IEMs (CIEM).

Comments on sound, build, and aesthetics are mostly subjective and based on how I appreciate this product. As always, YMMV.

Source:
• Sony Walkman ZX300

Build, Fit, and Accessories:
NF Audio did a great job for the build quality of the NA1. The outer part of the shell is made of aluminum with an elegant design bearing the NF Audio logo, NF. It is coated in a matte finish which adds an elegant feel to it. The outer shell joins seamlessly with the inner part which appears to be a semi-opaque resin. It’s as if the whole shell was made out of single block of material, having no feeling of being clamped together when you run your fingers between the outer and the inner parts. Two vent holes can be found in each earpiece; one located near the nozzle which looks like just a hole poked into the resin, and the other one close to the outer shell which is made of metal with a small bore in the center. The included cable is a 5N silver-plated OFC with 2-pin connectors and a 3.5mm single ended plug. Cable design is decent and doesn’t look like a generic type of cable, having NF Audio labels on the plug as well as on its Y-split. It also has a Velcro strap attached to it.

Throughout my testing period, I did not encounter any signs of driver flex. And that’s good news for this dynamic driver IEM.

I decided to use my own wide bore ear tips, which appears to be just appropriate since the nozzles are a bit wide in diameter. They sit comfortably enough using medium tips, though still protruding a little bit off my ears.

Other accessories include two extra sets of ear tips (S, M, L) for balanced and bass tunings, a cleaning brush, and a box-shaped traveling case with snap-on magnets.

Sound:
• Bass – The overall bass response is well balanced and clean, no bleed going into the upper frequencies at all. Bassheads will probably feel the lack of quantity on the subbass though. For me, there’s definitely enough rumble to feel whenever tracks needed it. This doesn’t strike me as a bass-anemic IEM. There’s also a decent punch on the midbass, with a quite fast decay and enough thump on mid to higher volume levels, but almost on the threshold of being smooth. Overall, it’s a well-rounded bass that fits my preference.
• Midrange – Vocals sound slightly upfront and at times on the thin side. Sibilant recordings, specially of female vocals, have the tendency of being slightly emphasized. It is probably unforgiving on such qualities of recordings. The rest of the frequency is rich in detail. Stringed instruments are highlighted well without being too upfront throughout.
• Treble – The upper midrange going up to the treble region is highly resolving while still having a smooth feel to it. The sparkle up top is good without any obvious graininess. Though the extension could have been improved more.
• Soundstage – Soundstage width is good which enhances its imaging capability as well as its instrument separation. There’s enough airiness which prevents the overall sound to feel confined or too intimate despite all the microdetails being offered.

iBasso IT01 comparison:
The IT01 has more subbass quantity and goes a little deeper. Vocals sound more laid back, but without any hint of sibilance or harshness. Treble is on the smooth side here in comparison to the better textured NA1. Extensions on both ends are slightly better on the IT01. Soundstage feels more airy, but with almost the same width. The NA1 edges the IT01 when it comes to definition of microdetails and overall resolution.

Conclusion:
The NF Audio NA1 has a well-rounded sound which, I think, will please both bassheads and trebleheads enough. Those who are looking for “earth-shaking” bass or boom-boom type of sound may look at some other place. Perhaps try the iBasso IT01 instead. However, if you’re the type who’s looking to pay more attention to details and who’s also looking to have a great all-rounder type of IEM, I highly suggest you try the NA1. Awesome dynamics! For the asking price of $169, I would say that money is well spent on these, having an excellent build quality, elegant design, and despite leaning slightly to bright at times, still maintains a flexible type of sound signature with good neutrality.



SPECS:
• Model: NA1
• Driver: Double cavity dynamic driver
• Frequency response: 9Hz - 40kHz
• Maximum SPL: 125dB
• Sensitivity: 110dB/mW
• Distortion: <1%
• Impedance: 18Ω
• Sound insulation: 25dB
• Cable: 2-pin 0.78mm 5N silver-plated OFC
• Plug: 3.5mm single ended
• Dimension: 138 x 225 x 50mm
• Net weight: 330g

NF audio NA1


The NA1 was provided from NF audio and Penon for the purpose of a review. These are my observations and views of the NA1.

The good old dynamic in ear is making a come back but with some new tech shenanigans to make em sound better. At least that is what I call it. Be it a new advanced coating or having dual voice coils. Double chamber. What does all that mean?

To me it just says 1) Either these guys are much more advanced in what they do than my own knowledge of such process or 2) They could be full of you know what. A dynamic is a dynamic right? I mean who is really gonna pay attention to all the tech stuff they put on the sales page here. And what does all that mean? More importantly what does all that do for the sonics of the NA1? Let's find out.

Well my friends, I am here to tell you we have a new up and comer to the market which goes by the name NF audio. Not Foolish in the way they market stuff. Hearing and getting to know the NA1 for the past several weeks has been enlightening for me. NF don’t stand for Not Friendly audio as what I am hearing is not that at all.

So the movement for the past several years was all about how many drivers a company can stuff into an earphone. Cus we all know more drivers must mean it somehow has more sonics associated right? Then why even look at a single dynamic NA1? It is simple because these sound better than your mutil BA and hybrid earphones that were all promising the stars when it comes to sonics.


First listen on open box for new earphones, either you cringe with regret or was for the NA1 one of astonishment. I was mighty impressed and it was due to the hyper clarity with abnormally high levels of precise imaging right out of the box. Wait a second these aren’t supposed to sound like this? I mean I wasn’t expecting them to have this type of a higher end sound. I was expecting a good sound but higher end sonic properties out of the box? This was getting interesting..

I will not judge a phone out of the box but sonically what I was listening to was something I wasn't ready for. That hyper clarity and detail left an impression. My immediate thought was. I’ve heard this before. I remember listening to the clarity of the Beyerdynamic flagship Xelentos a while back and even shared some similarities to my Beyer DT1990 pros. There has to be a catch I thought and off to the burn in station they went.


The package comes in a semi larger box with what looks like a CD with 2 shells in it. The package includes a very good looking box case with a magnetic lid to carry your phones in. The included cable is standard fair but is not as bad as some previous cables I have gotten with review samples in the past. While the cable is usable, I am not a fan of the stiff ear guides. While the 2 pin .78mm cables can be changed out, I am also not a fan of these QDC type shrouded 2 pins. Aftermarket cables stick out more than they have to due to the protruding female 2 pin on the housing itself. Hope they go with a recessed socket for future earphones.



NA1 comes with 2 sets of 3 sized silicone tips. One that says balanced and the other that says bass enhanced. So do the tips matter? Absolutely. The highly resolving nature of the NA1 means your gonna have to experiment with tips to get the sound you're looking for. Even NF audio is suggesting this due to their tip choices. The balanced tips have a wider nozzle that sits more shallow on the NA1 brings out more treble emphasis and the bass tips use a longer sitting more narrow bored silicones which lessens treble emphasis, therefore enhancing mids to bass a bit more. Tip rolling is highly recommended. Finding a tip that is somewhat between the bass tips and the balanced tip is what I ended up using for the review. A pair of Spinfit CP145



The build is solid using an all resin shell. These aren’t gonna win any awards for fancy looking shells by the way they look but they have it where it counts. That saying don’t judge a book by it’s cover applies here. As these are a prime example of looks don’t equal how they sound.

These don’t sound like your garden variety dynamic or do they sound like anything garden variety. These are much more higher end sounding than you would imagine. They are tuned with extension detail and resolution as a base for the sonic properties. Something you might associate with much higher end more resolving in ears. With that in mind, I have to say these have set the bar for what NF audio has pulled off in the price range. All that tech jargon actually seems to matter cus these in ears have the type of sonic resolution that is not common at all in the price range.

First thing that hits your auditory senses is the expansive medium wide stage they have. The sound vents on in front and one in the side seem to add to the staging of the earphones. Tonality is a bit on the cool side of neutral and it has more to do with that hyper clarity I mentioned previously. Burn in does tame the slightly grainy treble I heard on open listen, so burn in is recommended. Back to the sound.



The staging is more wider than it is tall or deep. A forward wider projecting stage with an average depth of sound. NA1s gives out a higher level of spatial awareness listening to your tunes due to the stage presentation. One of the best examples of black space and or instrument separation for the monetary level I have heard. Instrument definition pops with a resolving detail and is projected cleanly sometimes projecting outside of what your hearing due to how clean. Instrument timbre is very good due to the extraordinary resolving nature of the sound design. Extension of the sound is another aspect worth mentioning. Will go into the bass and treble here later but extension in both regions are superb.

NF audio went for a reference type tuning on these meaning it is one based on resolution and extension on both ends. Something similar to tunings you would hear for higher end audio cans like the resolving nature of a Sennheiser HD800 with the sound balancing similar to the Fostex TH900s. Lower mids presents with a neutral amount of emphasis and sound design has greater precedence in the upper mids. With exacting clarity in the mids regions, while some will want a greater emphasis in the mids. Due to the high level of detail present, the sound of the NA1 is somehow satisfying. In fact the NA1s remind me a lot of my favorite can the Beyer DT1990 Pros. I would say the NA1 is like a brother from another mother. It has very similar sound characteristics. Mostly neutral with deep reaching bass and extended detailed trebles.



For folks looking for a warm full thick rich syrupy type of sound.This in ear is Not For you Audio. These have a forward treble enhancement which accounts for their cool somewhat brighter tonality. Treble shimmer with ample sparkle. The extension of the treble is worth noting. There is not a high note in the treble ranges these will hide. I feel it is one of the better monitors that does treble for detail lovers. NA1s has pulled off, extension and definition in the region to complement this highly resolving monitor. Folks that are into their micro details from the treble region will get that with the NA1s. Treble rides a fine line between highly resolving and slightly edgy. It is the type of treble end where once you acclimate to the auditory definition other monitors will sound a bit dull afterwards.

Personally I appreciated the highly resolving nature of the sound design. This makes the NA1 somewhat unique in the price range. Due to the forward wide projecting staging and ample treble definition I feel these can get a bit fatiguing when listening to overly processed EDM tracks with synthetic high notes that linger too long. The NA1s will expose any flaws of a track or with tunes that have greater abundance of treble emphasis so these will not be the best for the genre.

For vocals and natural instruments however. Now we are talking. Listening to Steely Dan on these are a treat as great recorded tracks will reward with one of the cleanest well separated yet cohesive renditions you will hear. Absolutely fantastic for Jazz renditions from likes of Chick Corea and Gary Buron, Charles Mingus or Wayne Shorter. That treble shimmer, low hitting bass notes and clean mid range makes for excellent listening with lower volumes.

Bass is another aspect of the NA1s that excel. Not All 1 note. While the main focus in the bass region is sub bass the steady rise to the sub region has enough emphasis where mid bass has an accurate amount of speedy impact. Mid bass bands are clean like the rest of the sound but has a good amount of sustain to sound very natural. When it comes to sub bass extension, sub bass has a freaky amount of texture and reach. These will rumble in the jungle. Which actually sounds stupendous for RnB and Hip Hop tracks that require a lot from the region. Sub bass just blossoms and will surprise you just how strong the sub bass is on these. Hits them low notes with aplomb. Seems the dual sound coils implemented for the NA1 is showing what it can do. Basically you get every detail from the deepest of bass notes to the highest of treble notes with very good spatial evenness and an effortless quality to the sound.



In the end, the ability of the single dynamic used for the NA1 makes the earphones stand out in a crowded field with too many me too in ears. It is simple folks. These are about as resolving as it is going to get for dynamic earphones in this price range. A taste of a highly resolving high end sound can be had on the NA1. No longer do you need to spend large kilo bucks for this type of sound as it exists in the NA1. If your the type that want every detail from your tunes pushed out of your sources. Give the NA1 a try. As always thanks for reading and happy listening.

Introduction

NF Audio is a brand of headphones under the company Shenzhen Ningfan Acoustics. It was founded in 2014. They have several models of medium and high range (JD22, JD24, NF4u, NF3u, NF2u, NF2Pro, NF3Pro, NF4Pro, NF6Pro, NF8Pro, NF4m ...). The meaning of the mark, according to them, could be: "Near Field", "Nice Fit", "Nice Frequency response"...

They have recently brought out their cheapest model, the NA1, which is the model I'm going to review. It mounts a dynamic driver, called the MCL2-10. Among the technologies used in the driver, we can emphasize the use of "bilateral voice coil leads" to reduce the distortion generated by the vibration, dual magnetic circuit, where two NdFeB magnets provide a magnetic flux higher than 1 Tesla and a double cavity design, to control the air pressure more accurately and thus, smooth the movement of the diaphragm. Finally, the 3D driver cover has been specially designed to reduce reflection interference. All this helps to make the sound very detailed, full and with a well-defined low frequency, abundant but controlled.



Specifications

• Drivers Type: double cavity dynamic driver
• Frequency Response: 9Hz - 40kHz
• Maximum SPL: 125dB
• Sensitivity: 110dB/mW
• Impedance: 18Ω
• Sound insulation: 25dB
• Distortion Ratio: <1%
• Connector Jack: 3.5mm Audio
• Cable: 5N silver-plated OFC
• Capsule Connection Type: 2pin 0.78mm

Packaging

The box is big, its dimensions are 230x146x55mm. It is completely black and the letters are grey. On its upper face, on the top, there is a transparent opening, which allows the capsules to be seen. They are inserted into a foam piece decorated like an audio CD. A tab, with the logo and brand name, simulates the laser reader that reads the CD. At the bottom of this face, in vertical letters, is written the name of the model and its small description. There are also coloured moles, which indicate the colour of the capsules. On the right-hand side of the model is the same descriptive content as on the upper side. On the left side, there are some of the characteristics and properties of the model. On the back side, the specifications are completed and some additional information is provided. The languages used in the packaging are Chinese and English.

Once the cover is removed from the packaging, you can see the foam piece, which simulates the CD, where the capsules are embedded. Next to it, there is a black cardboard envelope, inside which there is a booklet with instructions, description of the model, advice on use, guarantee, introduction to the brand, its meaning, its future, etc. It is also written in Chinese and English. Several things are worth noting: on the cardboard envelope, there is a silk-screen printing reminiscent of the controls of a CD player. On the foam piece where the capsules are fitted, both the side and the polarity of the pins are indicated.

Once the envelope is removed, a gray rectangular transport box with a magnetic closure appears, with the logo and brand name inscribed on a grained plate. There is also a small cardboard box, inside which there are blister packs with silicone tips and a small cleaning tool, which has a brush and a fork. There are two sets of silicone tips, three pairs each, size SxMxL. One is white silicone, called "Balanced ear tips" and the other is black, called "Bass ear tips". Apart from the colour difference, their inside diameter is also different. Balanced ear tips have a larger inside diameter.

As a summary, the complete content is:

• The two capsules.
• A 5N cable with a 2pin 0.78mm connection and a 3.5mm plug.
• User's guide.
• Transport box.
• Cleaning utensil.
• Balanced ear tips (SxMxL).
• Bass ear tips (SxMxL).

The packaging is original, with that tribute to the CD. It may be a little big, but it is something that is normal in most products in this price range. The transport box is rigid, its interior is velvety, it is very useful, distinctive and original. In addition, its dimensions and shape, are very appropriate for storage.

The cleaning tool is appreciated, but some foam tips and a higher quality cable are missing.



Construction and Design

The design differs slightly from the IEMS I've tried recently. The shape of the capsules is very stylish: both in the shape of the outer face, and in the finish of the nozzles. The outer face is made of aviation aluminium, manufactured on a 5-axis CNC machine. The shape is narrow, which helps the fit in the ears. The body of the capsule is made of dark, semi-opaque resin. Its shape adapts very well to the auditory pavilion, following a very ergonomic shape. In addition, both the body and the nozzles are conveniently designed to achieve deeper insertion and a high level of isolation. This type of shape makes it easier to adjust, prevents movement and makes the choice of tips much easier and optimal, as it is very feasible to achieve the perfect seal. In this way, it is easy to take advantage of the characteristics of each used tip, being able to observe the characteristics of each one of them.

Returning to the capsules, on the inner side, a hole can be seen, near the base of the nozzles. There is also another hole, this time like a metal button, located on the rear side. The 2pin 0.78mm connection is surface mounted on an oval shaped transparent plastic base. The nozzles are metallic and have an H-shaped profile. The diameter, just at the outermost part of the nozzle, where the metallic grid is located, is 6.1mm, while the diameter of the inner area is 4.9mm.

The cable consists of 4 braided strands, covered with black plastic. The two-pin connector is covered by a rigid, transparent plastic sleeve. This sleeve is angled so that it separates from the vertical plane that crosses the connectors. This way, it tries to separate the cable from the head, to provide a better fit over the ear. The cable, in the immediate area of this sheath, has a semi-rigid translucent plastic guide, to ensure its position behind the ear. The dividing piece is a black plastic disc, with the brand logo inscribed on both sides. The pin is an oval, metallic piece with two holes. The Jack connector is 3.5mm, gold-plated and its cover is a two-colour grey cylinder, with a lowered and polished face, where the brand name can be read. Finally, the cable has a customized Velcro strip, to collect it easily.

The design of the capsules, I think that seeks more the best possible ergonomics and comfort, as opposed to beauty. The capsules are very practical and very well constructed. The weight of each one of them, is in a good medium term. In addition, there is the possibility of choosing the colour of the outer face in grey, blue and red. The cable, however, tarnishes the quality of the set. Nowadays, a lot of importance is given to this element, both in the design and in the thickness, number of strands, material used, etc. In this case, a 5N cable is used, with quite thin strands, which in my opinion, is not up to the performance of the capsules.




Adjustment and Ergonomics


The NF Audio NA1 has been designed to optimize its ergonomics, of that I have no doubt. The narrow shape of the capsules makes it fit very precisely in the ears. The shape and length of the mouthpieces, favours a deeper insertion, ensuring an optimal and high sealing, as well as a greater sound immersion and high isolation. This shape favours the use of smaller tips, and also allows the sound characteristics of each tip to be preserved, as the fit is very simple, firm and stable.




Sound

Profile

The profile of the NF AUDIO NA1 is balanced, with very linear bass, with good depth. Its main emphasis is on the high mids, first highs, generating a very clear sound.



Bass

Basses from a dynamic driver are always welcome. This time, though, they are not the most emphasized part of your frequency curve. Every day, these drivers are more refined, providing better sound qualities, gaining in speed and realism, offering greater fidelity. This is something that NF Audio demonstrates in this model. The NA1's bass is powerfully controlled, fast and very tight. If it weren't for the DD sound, you'd think you were hearing a big bass BA, because it has the best of it. The low zone is very linear, only the most sub-bass part has a small drop, without it tricking a good feeling of depth. That way, the balance is quite big, getting a very uniform, compact and very precise hit. The timbre is very natural, with a smooth and soft texture. The sound planes of this lower zone are described with great precision and detail, they have great lamination and their layers are easily broken up. Its overall presence is located behind the middle zone, far from a bass-head level, but with a good amount for a balanced profile. Those who want to get more bass presence can use the narrower channel tips, called "Bass Ear Tips", that come with the accessories. With the "Balanced Ear Tips", the reduction of the bass zone is very evident.

There is enormous quality in this zone, provided by the good qualities of the magnificent dynamic driver.



Mids

The profile of the NA1s highlights the midrange, generating it with great clarity, with a brilliant hue, which characterises the sound as a whole. This emphasis on the upper mid-range favours a very clean execution of the voices, especially the female ones. Its timbre is situated on the luminous side of neutrality, but without sounding unnatural, nor too fine, since no lack of body is perceived in them. Although they stand out in presence, their perception is not strictly close, but they are well placed within the rest of the instruments, with good separation and a very realistic and natural reconstruction. The proof of the remarkable symbiosis between voices and instrumentation is the high degree of detail perceived in the mids. All of them feel as close as the voices and the instruments, giving them a great sense of naturalness and realism. This is something that underlines once again the excellence of the dynamic driver created by NF Audio, as it is capable of providing a wealth of nuances and resolution, almost unusual for a driver of this type, in this price range.

Again, thanks to the "Balanced Ear Tips", this range can be highlighted, as the bass is quite reduced. But it can also bring the wheezing to a higher point than is permissible, for some sensitive ears. In that case I recommend the "Bass Ear Tips". But you can also play with other tips, with different diameters, bi-flange or tri-flange. The NA1s have an ergonomic design that allows a deeper, medium or shallower insertion, depending on the tips used, which provides a lot of possibilities to tune the sound by "tip rolling".



Treble

The first trebles are quite energetic, but the sound generated is neither lacerating nor too sharp. They could be classified as lively and dynamic, crunchy, even exciting. After this almost dazzling start, comes the typical calm, which comes to refine the range, so that it becomes neither excessive, nor too penetrating. The timbre remains realistic, within the natural side. There is a good amount of air, although the extension of the treble is restrained.

As a result, the treble is quite detailed, though not analytical, which is appreciated. The richness of nuance is remarkable, and this is revealed in all ranges, which gives a good idea of the good level of resolution that the NA1s possess.



Soundstage, Separation

The NA1 scene is semi-circular, but with more width than depth or height. Its perception is eminently frontal, but very clean, thanks to its high level of clarity. The separation also plays a very important role in this appreciation, as it helps to produce this feeling. Although, on this occasion, this level of separation is observed to be greater than the scene itself. The result is a very well defined, clean, bright, rich, full of resolution sound, with good instrumental and vocal placement, which enjoys a remarkable distance between notes.




Comparisons

Ikko OH1

The OH1s are one of the clear rivals, as they have a similar profile; moreover, they are hybrids. I wanted to see what the NA1s sound like in relation to the mids generated by a well-balanced BA. The first difference is in the adjustment of each one: the NA1s offer a deeper insertion, but, depending on the tips used, this can be modified. The Ikko nozzles are much shorter, offering a more superficial insertion. The second difference is in the volume, the NA1s move easily. The Ikko requires a little more energy to match the listening. The third difference is in the profile. Ikko are slightly more balanced, but also more V-shaped. They have a greater accent on sub-bass, more weight and overall presence in the lower range. While the NA1, have a more linear bass and more body, from half of the range onwards. They are more agile and fast, with better definition. While in the Ikko, the lower zone has a point of comparative darkness, although greater depth. In the middle zone, in its first half, the NA1 have more clarity, are more luminous and clean. They also have more closeness, presence and, again, more body. The voices in the Ikko sound lighter, colder, thinner, comparatively incomplete, somewhat more distant, perceiving their character more in V. In the NA1 there is more heat and greater width, they sound fuller and with greater presence of low area. They also offer a richer texture, with more nuances and details. The OH1 only offers a smoother and more anodyne texture, which does not stand out especially, where the NA1 reveals greater resolution capacity and, above all, expressiveness. On the other hand, Ikko are more analytical in the upper mid-range, sound more concrete, and the notes are finer, separate and isolated. But they lack the musicality that the NA1 do. In fast and synthetic passages, the OH1s demonstrate again that colder and aseptic character. The NA1s do not reach their level of precision, but they offer a close level, but with much more life. The upper zone of the Ikko follows this same trend, of coldness and greater analysis, their treble sounds sharper, more pungent and crisp. In the NA1, they are smoother, wider, but even more extensive, providing a more comfortable feeling.

The micro separation in the Ikko is higher, but there is more air in the NA1, filling a larger space and thus generating more width and a more ethereal sound than that offered by the OH1. In this way, your scene is bigger and semicircular, as opposed to the moderately deep sound of the Ikko, but also narrower.



Conclusion

Currently, there seems to be a curious trend: dynamic drivers, they want to possess the qualities of BA drivers and they want to sound like dynamic drivers.

On this basis, my impression is that the NF Audio NA1 seek precisely that, extract the best qualities of BA drivers: speed, accuracy, clarity, separation, resolution, detail, richness of nuance ... But with a timbre and naturalness, which only good dynamic drivers can provide. And, of course, the typical quality in the lower zone. Even its profile, flees from the classic Harman Target, offering another different and pure alternative. In my humble impression, the NA1 has achieved the best of both technologies, using the classic dynamic driver, but totally improved. In addition, they have designed one of the most versatile IEMS in terms of fit and ergonomics, which I have had the pleasure of testing in their price range. In addition, they are small, excellently constructed, have a careful packaging and an original transport box. There is no doubt that the NA1 are one of the new dynamic alternative kings.



Sources Used During the Analysis

• Burson Audio Playmate
• Tempotec Serenade iDSD
• ACMEE MF-01

Ratings

• Construction and Design: 85
• Adjustment/Ergonomics: 93
• Accessories: 75
• Bass: 83
• Mids: 87
• Treble: 83
• Separation: 88
• Soundstage: 85
• Quality/Price: 85

Purchase link

https://penonaudio.com/nf-audio-na1.html

You can read the full review in Spanish here:

https://hiendportable.com/2019/12/20/nf-audio-na1-review/