NF ACOUS NM25

Disclaimer

The NM25´s has been sent by NF ACOUS. I really appreciate their support to bring you content about their products.

All of my opinions are my own; I do not receive any payment to promote any product in an unethical manner. And this case was no exception.

My video review: SLP NM25

You can buy them directly on their website:

NM25 - Price $199 USD

NM25 Ossuary Silver Edition Price $299 USD

Pros

• Fast transient response

• Very comfortable

• Extremely easy to drive

• Top tier accessories and packaging

Cons

• Perceptible hiss or noise floor on some audio interfaces

• Slightly short cable for stage and studio porpuses (maybe a 150cm cable could be a better option)

Accessories

Cable - 120cm 0.78mm dual pin 5N Silver Coated OFC

Storage box

4 pairs of Ear tips

6.35 - 3.5mm gold coated adapter

Design

They are very lightweight and compact, comfortable to wear for long periods, and made of a drop-resistant material, although they are somewhat prone to scratches, especially on the faceplate where the brand logo is located.

Even the ear tips are marked with “NF Audio,” the brand's former name—that's the level of attention to detail NF ACOUS brings to its IEM monitors.

Although 4 pairs of ear tips are included, in my case—as with almost all brands and models of IEMs—I usually use the L-size ones. However, with these NF ACOUS ear tips, I don’t feel like they provide a very tight seal, so I’m currently using the L-size TRN-T ear tips instead.

Sound - How I perceive it?

They feature a single 10mm beryllium-coated dynamic driver with a dual magnet and dual acoustic chamber.

The brand notes that their internal structure is designed to emulate a physical EQ in order to minimize sibilance.

All of this is just specs, but here’s how I perceive the sound of these NM25s?

As clearly stated on its website, the packaging, and the design of this headphone, Its sound is entirely geared toward live monitoring, studio work, and more casual sessions. But above all, it’s designed for that...monitoring.

It’s a sound that definitely won’t be to everyone’s taste; its extensive reproduction of high frequencies helps you hear barely perceptible noises during mixing and mastering sessions.

Bass

The bass is present but in just the right amount; you’ll only notice it if that was the intention when the song was mixed and mastered.

It has some low-end extension but it’s very subtle; the punch is quite fast and clean. It doesn’t have that lingering bass; the notes last just as long as they’re supposed to.

That said, I don’t think you’ll be able to achieve a 100% accurate mix with these IEMs, especially in the bass department. You’ll still need to use studio monitors to properly position the kick and sub without overdoing it, because you don’t fully perceive them in these earbuds.

Mids

The midrange is perfectly balanced in terms of volume; it’s clean, and it’s very easy to detect even the slightest distortions and clipping.

If the midrange sounds a bit cold to me, it’s because it lacks some detail in the lower midrange, which would make male vocals sound more realistic; female vocals are what you’ll enjoy the most with these headphones.

Treble

The highs are a bit pronounced, which is why they’re very revealing for mixing, for example.

They sound relatively smooth to me; they’re quite clean and don’t cut any slack for poorly recorded tracks or low-bitrate files—you’ll quickly notice any artifacts in that frequency range.

These highs softened up a bit after I burn them in as recommended by the manufacturer, who suggests up to 50 hours.

For my part, I always do burning in the earphones I test; I try to use them very little when I receive them and let them burn in for at least 15–20 hours.

I have to say that despite the internal structure of these NM25s that NF ACOUS mentions to attenuate sibilance, I can still perceive some sibilance in certain tracks that I know aren’t sibilant.

Soundstage

Their response to transients is extremely fast, which is why you can clearly distinguish the different layers of a kick drum and percussion, for example.

It doesn’t have as wide a soundstage as a planar driver, but you’ll be able to achieve very precise panning with these IEMs.

I can highly recommend them for gaming, whether you use an external DAC with a PC or console or connect them directly to the controller, because their sensitivity ensures you’ll get plenty of volume.

Power requirement and pairing

They’re quite sensitive, you can use them with any device, and they’ll produce a loud volume.

One thing I noticed when using them with my Arturia Audiofuse interface is that they have a slight hiss or noise floor, regardless of whether I connect them via a 3.5mm or 6.3mm jack.

This noise was only noticeable with my Audiofuse interface; none of my other devices exhibited the same issue.

With the Fiio KA13, a well-known model on this channel, the sound remains the same. Since they have a somewhat neutral sound signature, the NM25s maintain their sound exactly as is.

With the Fosi K7, the highs are slightly attenuated, and the low-midrange remains neutral, unlike other headphones I’ve tested with this same DAC.

The EQ on this DAC doesn’t overdrive the bass on these headphones at all; I can boost it quite a bit and there’s barely any distortion. I use this mostly for gaming with the NM25s.

I also tested them with a 4.4mm cable, and while the soundstage expands considerably, I notice some distortion and clipping due to its sensitivity.

I think the best approach is to use them as-is with the 3.5mm connection—you won’t be missing out on anything.

Conclusion

Highly recommended if you're looking for reliable in-ear monitors and want a break from over-ear headphones—the ones we use for mixing and mastering tend to be quite bulky and can get tiring during long sessions.

Plus, most of them have an open-back design, and if you live in a busy area, it can be hard to concentrate when you can hear outside noise.

I think these NM25s are great for the price; if you’re in Mexico, I recommend buying them directly from their website.

A big shout out to Eileen from NF ACOUS for arranging the shipment of this unit for my review.