A Brilliant Future

Ratings

Pros

• Specialised IEMs for monitoring, improved over the NM2+.
• Enhanced smoothness and refinement of sound while maintaining an analytical, precise, technical and resolute profile.
• They offer a very clear, transparent, bright, sparkling, vivid, fast, dynamic and energetic sound.
• More texture and elasticity in the bass for a more realistic sound.
• Great extension in the treble.
• They are still very light, well built and ergonomic.
• Tuning for monitoring and Treble-Heads.

Cons

• It’s not a suitable profile for everyone; while its tuning is a positive point, it can also be a negative due to its specialisation and brightness, which can become uncomfortable.
• The packaging and accessories are the same as those of the brand’s previous models. Even the entire design is the same as that of the NM2+, except for the new brand logo.
• Price increase compared to the previous model.

Purchase Link

https://nfacous.com/products/nm25

Link to the WEB

https://nfacous.com

Introduction

NF ACOUS was founded in 2014 (formerly known as NF AUDIO) and began its journey with customised in-ear monitors for stage performances. Since then, it has grown into a professional audio brand that integrates product research and development, creative design and precision manufacturing. The brand’s core values are sound aesthetics, engineering technology and user experience. It specialises in the production of headphones and collaborates with hundreds of artists, bands, television programmes and producers.
The brand’s latest model is the NF ACOUS NM25, which belongs to the Professional Series. These are premium metal in-ear monitors that represent a complete update of the classic NM2+ model. During this time, the brand has gathered feedback and reviews of the NM2+ model to further improve the listening experience while enhancing the monitoring function.
The NM25 is designed as a new concept in monitoring: a professional and reliable tool that provides musicians with studio-quality sound and a reference point, while offering accurate feedback on their performance. Whether for monitoring instruments or vocals, recording, mixing, arranging, video editing or live streaming, the NM25 is perfect for these applications.
The NM25 is made from a single piece of aeronautical aluminium, precision-machined using a five-axis CNC machining centre. It has a high-quality texture and is very lightweight. The combination of shiny and matte surfaces makes it shine with intensity and luminosity. The internal design has also been improved to reduce reflected sound and achieve a purer sound through five damping nets that control air pressure and two tuning sponges. This adjusts the air pressure balance between the front and rear, providing a higher quality reference sound.
The mechanical structure of the cavity and housing have been optimised for greater durability. Thanks to NF ACOUS’s experience in designing IEMS for monitoring and customised IEMS, the NM25 features a fully optimised ergonomic design.
The NM25 utilises patented CLUTTER TRAP 2.0 technology, which has a creative structure similar to that of a physical equaliser that precisely attenuates peaks and delivers a smoother listening experience with powerful, detail-rich sound.
The dynamic driver used is the MC2L-100A. It has a dual magnetic circuit and a dual electronic tuning acoustic chamber with a new separate zone damping system. Thanks to its high dynamics, it effectively and accurately controls the dynamics of different frequency bands, with a bandwidth of up to 9-40 kHz, and offers meticulous details with high resolution.
Electronic adjustment offers more possibilities for dynamic controllers. The MC2L-100A uses a more accurate integrated adjustment PCB board that is more stable and reliable, further improving sound quality.
The manufacturer’s introduction is quite extensive and full of details. However, in this review we will address other issues that have not been mentioned here, as well as the most fundamental one of all: its sound.

Specifications

• Model: NM25.
• Package dimensions: 150×132×83mm.
• Package weight: 300g.
• Driver: MC2L-100A dynamic driver with dual acoustic chambers and beryllium-coated diaphragm.
• Cable: 0.78mm double pin 5N silver-coated OFC.
• Sensitivity: 108 dB/mW.
• Impedance: 32Ω
• Sound insulation: 25dB.
• Frequency response: 9-40kHz.
• Distortion: <1%.
• Maximum SPL: 125dB.
• Connector: 3.5mm.
• Starting price $199.

Packaging

The NF ACOUS NM25 comes in the brand’s classic CD-shaped packaging, measuring 150x132x83mm. It has a ring for hanging. The NM25 is silver in colour, so the packaging features a lot of this colour. On the front, the name of the model is written in large, shiny silver letters. Below this is information that they belong to the Professional Series, as well as a brief description of the model. In the centre is a real photo of the capsules with the cable. On the back, the name is repeated in the same way. This time there is a realistic photo of the capsules without the cable, a description of the model’s features and a summary of the contents on the right-hand vertical margin.
The box is removed from one side. It is light grey and has the brand logo in silver in the centre. It opens like a book in the middle and shows the foam CD containing the cartridges on the right-hand side. On the left-hand side is the user guide. Below is the new zippered case. Underneath the CD with the earbuds is a blister pack containing four pairs of MS42 silicone tips, and underneath that is the cable. In summary:

• The two NM25 capsules.
• A silver-plated 5N cable with a gold-plated 3.5mm SE plug.
• A 6.35mm SE adapter.
• A zippered case.
• A user guide.
• Four pairs of MS42 silicone tips, sizes XS*S*M*L.

The packaging is the same, only the colours have changed. The new rectangular zip-up case remains. I think that, to justify a price increase, some extra features could be included, as well as some differences that would make it more meaningful.

Construction and Design

It’s difficult to find differences between the NM25 and NM2+ capsules. Only the brand logo on the outer face and inside the blue box on the edge of the capsule has changed. Previously, the brand logo on the outer face was engraved, but now it is embossed. The rest is almost identical; I only find that the bevelled edge of the outer face is more polished and shiny, and that the model name is not inscribed but printed in larger letters.
The NM25s are made of aerospace-grade aluminium and painted in a light, very shiny silver-grey. A 5-axis CNC machine was used for machining, which has made it possible to manufacture more precise, resistant and lightweight capsules thanks to the quality of the aluminium used and its alloy.
The nozzles are 3.5 mm high, with a smaller diameter at the base of 4.75 mm and a larger diameter at the outer crown of 5.35 mm. Both are covered by a perforated metal grille.
The surface of the capsules has a microtexture and the separation between the two sides is visible without this being a weak point. The outer side has two levels: the outer part protrudes and the central part is slightly depressed. In the centre, the brand logo is embossed. At the top of the edge of the capsules is a 0.78 mm two-pin connection. It is a rigid, transparent plastic plate with an oval shape. This means that the cable pins must have a female sleeve compatible with this shape. Near the connector there is a hole and, following the same edge downwards, you reach the blue dot, a small circle inside which is also the NF logo surrounded by cyan ink. On the other side of the connector, also following the edge, are the letters indicating the channel (L and R). On the lower edge, in bold letters, are the words “NM25 MONITOR”, only on the edge. Finally, there is another small hole on the inside, at the foot of the nozzle column.
As expected, the NM25 cable is identical to the NM2+, with only the brand logo and the shape of the splitter changing. It is a 5N Litz cable made of oxygen-free copper and silver-plated to improve the skin effect and reduce its impedance, and the only thing that has changed is the brand logo and the shape of the splitter piece. It consists of four tightly wound strands that result in a soft, shiny, almost white cable with a very suitable and manageable thickness, although it is not very rollable. The plug cover is unchanged from other models: it is cylindrical and grey, except for the flat part where the brand name is inscribed. The splitter is a triangular black plastic medallion with the logo on both sides. The pin is metal and has two holes inside. The two-pin connector is covered by a rigid, transparent plastic sleeve. This sleeve is angled and has the classic separation from the vertical axis. The cables coming out of these connectors are protected by a semi-rigid, transparent sleeve that shapes them over the ear.
It is clear that the NM25 model is an update of the previous NM2+ model, but its design is an almost perfect copy of the previous one. It seems that the differences are on the inside: it incorporates a new MC2L-100A driver instead of the MC2L-10II, as well as the new patented CLUTTER TRAP 2.0 technology, five damping networks that control air pressure, and two tuning sponges. Looking at the capsules, it is hard to believe that there are any differences.
The cable is very manageable, although it is currently in the thin segment, as the current trend is to use increasingly thicker conductors to reduce impedance. It is true that this cable model is very pleasant and easy to handle, but I think that, for the price, it is slightly below the competition. While other cables from competing brands tend to improve and offer interchangeable plugs, NF ACOUS continues to use the same cable it used in a model from five years ago. They do not even offer the option of a balanced plug.

Adjustment and Ergonomics

Copy-and-paste design, carbon copy. Like the rest of the brand’s IEMS, which have a very similar shape, they fit very well. The stylised nozzles allow for deeper insertion and the possibility of using different silicone tips, which facilitates tip rolling. The fit remains durable, with remarkable stability and no discomfort. There is almost no friction with the parts of the ear. The insertion, which is slightly deeper depending on the tips, increases the level of isolation (up to 25 dB, according to the manufacturer). The comfort and stability are more than remarkable.
As for the cable, the connectors have the same shape and detail that separates them from the head.
I cannot argue that the NM25s are very comfortable; what I do argue is that there is no external change.

Sound

Profile

The NF ACOUS NM25 incorporates Clutter Trap 2.0 technology, which prevents the elimination of the resonance peak around 5 kHz. This is a physical equaliser that attenuates this peak to provide a smoother listening experience, with powerful, richly detailed sound. That’s what the brand says. However, my measurements and those of my microphone indicate that the range between 5 kHz and 6 kHz is more prominent than that of the NF ACOUS NM20 and NF AUDIO NM2+. However, the 5 kHz peak is more attenuated in the NM25 than in the NM20 when taking the central point of 1 kHz as a reference.
The NM25 has a bright, rising W-shaped profile, with a good bass foundation, but with high and sustained excitement in the upper midrange and much of the treble. The NM25 has the most treble of the trio, along with the NM20 and NM2+.
It is a bright sound, with a cold tendency and analytical character, which seeks to be exemplary for monitoring. It is true that, overall, the NM25 seems to have more refinement and is no longer as bright or piercing as the NM2+.

Bass

The bass from NF AUDIO, now NF ACOUS, has always been of high quality and a benchmark. The NM25s are lighter in this regard, but their quality remains very high. The bass is very precise, concise and fast, with minimal residue and almost no decay. It does not have much texture, but it has great resolution, a lot of dryness and adequate weight, slightly above neutrality.
In the very low frequency pure tone test, there is a slight vibratory character in the first note, with low physical sensation and slight auditory load. Some colour is noticeable due to the oscillation. In the second note, the negative character related to the oscillation is corrected and the sound becomes more audible, with greater physical and sensory impact. From here on, the sound is more canonical, but I still find a certain vibratory character that prevents the test from being excellent. On the other hand, I do not find the sound to be very dark, which detracts from the depth of the bass.
The translation to reality has very marked foundations, but they lack that dark and deep aspect; rather, they have a little more colour. It does not have much volume, but it does have a certain elasticity that improves the texture and impression of the lower bass drums, giving them a little more body and ambient presence.
It is in the test of dirty, complex and unfiltered bass that the NM25s offer the best performance. Their technical ability controls any complex situation so that no bass line sounds diffuse, distorted, unreal or unnatural. The level of precision and resolution generates finer lines, very well-channelled, well-defined and contoured bass. They have enough capacity to generate a good impression of volume and give the feeling that the bass lines are deeper and more natural than the bass drums, which improves the realism, naturalness and timbre of this section. The NM25s perform better in this more realistic and less forced test, which is positive, as it is closer to the reality of a musical performance than simple tones. In this sense, their performance is also more appropriate for describing mantles, surfaces and bass lines than bass drums, as it is in these cases that a darker colour and a deeper feel come to the fore. However, technical quality is paramount.

Mids

In the midrange, there is a stark contrast between the first and second halves. The difference is 15 dB between 800 Hz and 2.5 kHz. Thus, male voices lag behind strings and guitars. Their base is narrow, with limited physicality and body, while details, edges and nuances are more activated and present. It is not a harsh presentation, but energetic at times: there are hits and syllables that generate slight pops and clicks. It is more penetrating, bright and incisive than sibilant, as it is so technical that the hisses are very fine and detailed. There is no murmur, but rather a sparkling expressiveness. And this extends to the entire sound, which is clearly technical and analytical. It is true that this capacity for analysis is much more noticeable in the high and sharp details and nuances, while the deeper micro-details or lower fundamentals are less resolved and visible, as well as relegated to later layers.
On the other hand, there is no doubt that so much energy in the upper midrange creates a vivid, speckled sensation that can cause fatigue if you are sensitive to this area. I would say that these headphones are perfect for monitoring at low to medium volumes, as they are capable of extracting a lot of information effortlessly.
From an instrumental point of view, they are very explicit, but the lack of warmth and bass generates fine, delicate and very obvious, transparent notes. Air easily enters between these notes and infuses them with a push that elevates them and places them close to the listener, especially the higher nuances and details, whose range and depth are more pronounced and audible.
As for the female voices, it is clear that they have more prominence than the male voices, but the difference is not as great as one might expect. What is certain is that they have more body and their development is more extensive, explicit and informative.
The analytical, expressive and decisive capabilities of the NM25s mean that the soundstage is wide, very well represented and full of details and nuances, which are particularly delicate, separate, airy, transparent, luminous and evident. It is clear that these are specialist IEMS in this regard, attempting to reproduce all nuances and scrutinise every detail. That is their true function, leaving aside musicality and other subtleties.

Treble

The treble is the star of the show. The high end is extensive, full of energy, and produces a very good impression and sense of air. But the best thing is that NF ACOUS has managed to ensure that these IEMS do not sound shrill or unnatural. It is clear that the overall timbre tends towards the bright side, but I still don’t think it is harsh, hard or sharp. They are energetic and can be somewhat tiring and even aggressive at high volumes. These are not IEMs that express the treble poorly, quite the contrary: they strive to do so. Clearly, this aspect is not to everyone’s liking, but that is their nature.
Without a doubt, the treble is crisp, crystalline, without hollows, sharp, elevated, extensive, airy and full of energy. It is perhaps one of the most complete, energetic and best-expressed high frequencies I have ever heard in IEMS with a dynamic driver. And that is very commendable.
The NM25s show their full technical potential in very revealing, decisive, precise and effective high frequencies. This is your chance, Treble-Heads.

Soundstage, Separation

The clear and obvious technical and analytical vocation of the NF ACOUS NM25 offers an impression of an expansive, volatile and gaseous soundstage, with many elements extending and fluttering with amplitude and ease. There is a great sense of separation, aeration, clarity, transparency and information. There are many elements close by and a good deal of depth is maintained thanks to the brand’s expertise in the low end. To my taste, it lacks a greater sense of depth and volume, but the stereo impression is very good and even the height is remarkable.
The soundstage does not surround the head, but it does exceed 180° thanks to the great laterality and the cleanliness and separation between channels that the NM25s possess.
The image is precise, very well drawn, with extensive and well-distributed instrumentation, and the voices are never thick or take up too much space, but are located in a coherent and realistic way.
The sound is very expressive, informative and well represented. It has a great ability to separate elements, but the layering of details is more complex because they are presented closer to the listener. The micro-details of the lower frequencies can be masked by bright, foreground macro-nuances. Persistent cymbals can hide minor elements in the background layers. I would like it to be more democratic in the micro-detail of all frequencies, especially in the first half of the midrange.

Comparisons

NF Audio NM2+

The NF ACOUS NM25 are an update of the NF Audio NM2+. They are very similar physically, and although the profiles are very similar, the curves are not exactly the same. The NM25 have more energy in the high frequencies and 2 dB more in the low frequencies, from the sub-bass to 100 Hz.
The NM2+ are more sensitive than the NM25: with the same output voltage, they generate greater sound pressure.
In the very low frequency pure tone test, the NM25 have a slightly more physical performance, but they seem to vibrate more. The tone is very similar in both, but the NM2+ seems smoother, with a little more colour. The NM25s seem to have a little more elasticity, which gives them greater realism. This elasticity also generates more volume, and the greater energy gives them more body, a spark of presence and forcefulness. However, it should be noted that the bass of the NM2+ is still good.
In the dirty, complex, unfiltered bass test, the NM2+ are more neutral and have less energy to control, which makes things easier thanks to their smoother texture. Even so, the result is very good. The NM25, with more power, pass the test with flying colours, if possible, and also sound more realistic, with more texture and a more natural and credible representation.
In the midrange, the NM2+ sounds rougher and more piercing, as if the notes were sharper. The new NM25 is more refined and has better resolution. The vocals have a little more presence, but they also sound more shrill. The tone and reproduction of the NM25 is more serene, smooth and delicate, with fewer edges and corners. In addition, the integration with the instruments is superior and more balanced.
It also appears that the NM2+ mids are slightly thicker than those of the NM25.
However, the difference in thickness is more noticeable in the upper range, where the NM2+ has more nuanced, wider and less brilliant treble than the NM25. The new version has more energy, rises higher, is more refined, has more detail, and finer and more delicate notes. The amount of treble is more homogeneous and extensive in the NM25.
In terms of detail, there is an improvement in the resolution and refinement of the NM25. The micro-detail in the background is better expressed, more visible and better stratified. The NM2+ are flatter, generating fewer layers compared to the NM25, and almost everything is perceived in very close planes. Their soundstage is wide but with little depth and is perceived as predominantly frontal. The NM25 have more depth and volume, are smoother, better stratified, with more differentiated layers and more discernible separation and silence.
Although the NM25s have more overall energy, they are more refined, smooth and delicate than the NM2+, which seem rougher, more angular, thicker and flatter. There is an improvement in terms of resolution, balance, layering, smoothness and musical detail in the new NM25s.

Simgot EA1000 Red Filter

An example of an analytical profile, albeit more versatile, is the Simgot EA1000. With the Red filter, they have a similar amount of bass to the NM25, but with much less energy in the treble. Even so, I still find it a relatively bright profile.
Price $250 for the EA1000 and $199 for the NM25.
The EA1000 driver is a second-generation 10mm dual magnet, dual cavity DMDC™ dynamic driver. 6mm passive radiator. Cathodic sputtered purple gold diaphragm.
NM25 driver: MC2L-100A dynamic driver with dual acoustic chambers and beryllium-coated diaphragm.
Sensitivity: The EA1000s are clearly more sensitive.
Fit/ergonomics: The NM25s are quicker and easier to fit, but the flatter design of the EA1000s means they fit very well in the ear once correctly positioned.
Construction and design: The NM25s have a good design, but it is repetitive. They are lighter and slightly more stylish, with a semi-custom design. The EA1000s have a different, flatter design with a mirror finish. They are heavier, but feel more robust, distinguished and diverse.
Accessories: better cable, three pairs of nozzles, two sets of silicone tips, a larger case and higher quality packaging for the EA1000. The NM25 is standard in these aspects.
Bass: the EA1000s have more weight and presence, which translates into a more powerful punch, more volume and body. The frequency response is very similar in both, but the EA1000’s better frequency balance gives the bass more weight in the overall sound. The bass on the NM25s is more precise, dry and somewhat more restrained; it also seems faster, but more contained.
In the very low frequency pure tone test, the NM25s are noticeable from the outset, albeit with a slight vibratory effect. The EA1000s are more physical but less audible; once they are noticed, they appear darker and with a smoother, more continuous surface. The speed of the NM25s is noticeable, but they are also slightly more coloured and less deep. On a technical level, I prefer the NM25; but in terms of realism, naturalness, power, punch and fun, I prefer the EA1000.
Mids: the EA1000 are perceived as warmer compared to the NM25. They are thicker, with a more balanced and neutral timbre, less bright and somewhat rounder. The NM25s are clearly more explicit and faster in transitions, and show more detail. I like mids with body and substance; although neither excels in this regard, the EA1000s are ahead. However, the informative power of the NM25s is evident compared to the more complete, full, dense, musical and balanced midrange of the EA1000s in relation to the NM25s. Without a doubt, these are two different analytical approaches; the NM25s are more specialised in this regard on a technical level.
High frequencies: both IEMs perform well, although the Simgot has a significantly lower energy level. The treble on the EA1000s has good extension and is well distributed, although it is thicker. The treble on the NM25s is crisper, brighter, finer, sharper and more extensive, with greater energy, and also more delicate. But it is also more tiring, more present and more penetrating.
Separation and detail: both IEMs have a high level of detail. The EA1000s have better layering, so the background micro-detail is sharper, while the macro-detail and separation of micro-detail are better in the NM25s thanks to their greater clarity, sense of air and space. The EA1000s, being denser, sound fuller and the separation is not as evident.
Soundstage: more gaseous and volatile for the NM25s, with good height and sparkling, expansive elements. More intimate impression of the image. The EA1000s have more volume, density, sense of fullness and depth.

Conclusion

The NF ACOUS NM25 represents an evolution from the NF Audio NM2+. It maintains the same informative and expressive intent, but with a higher level of refinement that improves the musical aspect and smoothness of execution, as well as the delicacy of notes and edges. With improved resolution and a very vibrant, sparkling, vivid, bright, clear, clean and transparent sound, NF ACOUS has patented technologies such as CLUTTER TRAP 2.0 to achieve an analytical sound that is totally specialised for monitoring, but improving on the aspects that made this profile more aggressive and tiring. Without a doubt, the NM25’s profile remains powerful and explicit, so enthusiasts looking for calm, smoothness and musicality should take this into account, as the NM25 is at the opposite end of the spectrum. And that is where their strength lies. While there are currently many IEMS around the META curve that seek a more complete balance, but border on boredom, the NM25 offers a totally different experience, in which detail, sparkle and informative capacity are the strengths of this model.

Sources Used During the Analysis

• Aune X8 XVIII Magic DAC + OpAmp Sparkos Labs SS3602 + Aune ND7.
• Burson Audio Playmate 2.
• Hidizs AP80 PRO MAX.
• iFi GO bar Kensei.
• NiceHCK Octave.
• EPZ TP50.
• TRI Third Eye TK1.