In this article, I review the NF Audio NE4 Evolution in-ear monitors (IEM). NE4 has 4 balanced armature drivers and features removable tuning faceplates. It’s priced at $749.

Disclaimer: This sample was provided by NF Audio for an honest review. All observations and opinions here are my own, based on my experience with the product.

NF Audio NE4 Evolution

Specifications

Frequency response: 9-20kHz -Pop faceplate (red)
18-22kHz- Reference faceplate (black)
20-30kHz- Transparent faceplate (blue)
Sensitivity: 104dB/mw -Pop faceplate (red)
108dB/mw – Reference faceplate (black)
110dB/mw – Transparent faceplate (blue)
Impedance: 6Ω -Pop faceplate (red)
10Ω – Reference faceplate (black)
22Ω – Transparent faceplate (blue)

In the Box

• NE4 Evolution
• 3 pairs of replaceable faceplates
• 5N silver-plated OFC cable
• 6.35mm to 3.5mm adapter
• 3 pairs of balanced silicone eartips
• 4 pairs of atmosphere silicone eartips
• 3 pairs of screws
• Allen wrench
• MD-style leather case

Design

The NF Audio NE4 Evolution features CNC-carved metal shells with a mixture of aluminium and stainless steel. The surface is smooth all over and the build quality is outstanding. NE4 adopts QDC 2-pin sockets for increased stability and longevity.

Naturally, the main point of interest in NE4’s external design is its removable tuning faceplates. Each one houses a different electronic crossover with a distinct sound profile. There are 3 faceplate sets in the package: Red/Pop, Black/Reference and Blue/Transparent. To change the faceplates, you simply unscrew the single screw with the included tool and replace them with your desired set.

While changing the faceplates might be simple, it’s not exactly easy – the screws are tiny and getting them in place will test your eyesight, the dexterity of your fingers and perhaps your patience.

NE4 is a large IEM but feels comfortable in my ears. The passive noise isolation is average, making this IEM suitable for everyday environments. The included Litz structure 5N oxygen-free silver-plated copper cable is solidly built but the handling could be better. Although it’s a quality cable, it feels inadequate to pair with such an expensive IEM.

Sound

Gear used for testing includes the Cayin RU6, Soundaware M2Pro and the Topping E70+L70 combo. NE4’s low impedance and high sensitivity means it doesn’t need much power to drive but it scales well so you will be rewarded if you pair it with a better quality source.

So let’s talk about these filters. This isn’t the first IEM I’ve seen with swappable crossover circuits. I reviewed the Anew X-One back in 2020 which showcased a similar concept. In all honesty, the X-One’s tuning system was nowhere near as effective in creating distinct sound profiles but the way the different filters were integrated was far more user-friendly. One could simply swap the filters out with your bare hands compared to fiddling with the minuscule screws on the NE4.

I stuck with the black Reference filter as it sounded the most natural and engaging to my ears. The red filters were fun for a while but I found that there wasn’t enough meat in the lower mids to counterbalance the pinna gain and they sounded somewhat fatiguing. The blue filters take leanness to the extreme, resulting in a brighter tone, albeit with maximum detail. The Explore filter (sold separately) is interesting but again, I found it a little too bright.

Presentation (Reference filter)

The NF Audio NE4 Evolution has a few standout characteristics. First of all, it creates an exceptionally wide soundscape that reaches far in all directions. It has fantastic technical performance (more on that later), a natural timbre and great midrange resolution. It’s one of the airiest IEMs I’ve tested recently despite a somewhat laid-back treble.

Bass

The NE4 prioritizes a tight and controlled low end, offering an alternative for listeners who value precision over power. While it may lack the deep, chest-rumbling sub-bass that dynamic drivers can produce, the NE4’s bass extension is nonetheless impressive, delivering lows that feel both natural and well-defined.

The NE4’s tight and impactful bass truly surprised me. It delivers a satisfying punch without muddying the sound, making it easy to forget you’re not using an IEM with a dedicated woofer. This combination of power and precision makes the NE4 one of the most enjoyable BA bass experiences I’ve had outside of custom IEMs.

Midrange

A neutral note weight and excellent instrument separation in the mids create a spacious organic sound—vocals sound crystal clear and articulate yet immersive and rich. Instruments like cellos sound lush and full-bodied yet transparent and uncoloured.

There’s a mild upper midrange lift to add vibrancy and clarity but it never sounds forced or overly assertive. Overall, the midrange is smooth but nuanced, organic and engaging.

Treble

The highs are crisp, airy and full of detail. There’s a warmth to treble notes as if they have a dense core surrounded by a glowing halo. This enables NE4’s treble to be soft and spacious yet precise and textured with great spacing and an agile spirit.

There’s no sibilance or sharpness (at least with the Reference filter) resulting in a smooth and airy presentation that extends the detail and sparkle of the highs without fatigue.

Soundstage & Technicalities

The NE4’s soundstage is expansive and spacious. Because it’s an all-BA IEM, the transients are snappy and clean, resulting in a black background with ample space between each instrument. So instrument separation is above par and placement within the stage is precise. While the NE4 might not be the absolute most detailed IEM on the market, it will reveal almost all micro-details.

Verdict

The NF Audio NE4 Evolution delivers pro-grade sound quality with a wide soundstage that lets instruments breathe, while its precise tuning ensures natural tone and timbre. But the NE4 Evolution goes beyond a single sound signature. The included tuning filters allow you to tailor the sound to your preference, whether you crave booming bass or sparkling highs.

Not only do the shells look great and feel comfortable, but they’re built to last too, making these truly suited as a robust daily driver for audio professionals. However, the pricing might be a bit ambitious, especially considering it’s a 4BA driver IEM from a relatively unknown brand. At this price point, potential buyers are less likely to make a blind purchase without auditioning them first. Nevertheless, those who have the opportunity to try or buy the NE4 Evolution will be pleasantly surprised by the exceptional audio quality it delivers.