Fir Audio may take some of its design cues from 64 Audio, but its sound signatures tend to be vastly different from the generally neutral presentation that 64 Audio delivers. What kind of sound profile can you expect from the Neon 4, and does its performance warrant the price tag?

What’s in the Box?

• Neon 4 IEMs
• 2-pin 4.4mm cable
• Leather case
• 3 sets of ATOM XS interchangeable modules
• Cleaning tool
• 5 sets of ear tips, including foam and silicone
• Warranty card

Look and Feel

Like all their models, Fir Audio demonstrates top-notch craftsmanship in the physical design of the Neon 4. The combination of a machined aluminum shell and a stylish sapphire glass faceplate creates a refined and high-quality appearance. The silver casing feels substantial, while the faceplate maintains a simple yet polished look. The fit felt perfectly comfortable, taking inspiration from 64 Audio's shell design with its streamlined shape. The shells were perfectly curved to conform to my ears, and the nozzle didn’t feel intrusive. So, no complaints here.

Design

The Neon 4 features a 10mm Kinetic Bass dynamic driver and 3 OpenDriver balanced armatures. The headphone's Kinetic Bass technology directs lower frequencies through a vent on the chamber side, targeting the cartilage and pinnae for more accurate reproduction of open-air speaker-like frequencies. The tubeless, open driver design, similar to that of 64 Audio, prevents air pressure build-up in the ear canals, further reducing fatigue. Additionally, the Neon 4 includes swappable ATOM modules to adjust the tuning according to personal preference. For the purpose of this review, I went with the default modules out of the box. The Neon 4 is reasonably easy to drive, but it benefits from a little bit of extra driving power. For testing, I paired the Neon 4 with the Astell & Kern AK HC2 DAC/amp dongle.

Specifications

Sound Impressions

Soundstage

Although the heavy bass insulates the soundstage somewhat, there’s a spacious sense of distance between forward and rear sitting instruments. There’s also almost an exaggerated sense of width here that creates grandness in scale, putting you smack center in a super deep stereo field. There's a great sense of depth here as well, with instruments sitting all the way to the back of jaw. Vertical movement is also impressive, with bass instruments able to reach very low down near the throat area. In fact, the imaging is one of the Neon 4’s greatest assets, an it's the primary element that makes this IEM worthy of its price tag.

Low-End

A pulsating and sonorous bass here. Listening to EDM, the sheer power of the low end almost sends you into a manic state. The sub-bass frequencies are so deep and visceral that I could feel a rumbling in my tonsils. But as thumpy as the bass is, it has a rounded, almost muffled feel. And perhaps because of this quality, there’s a slight veil to the low-end frequencies. In terms of transparency, the indulgently rich tone seems to smooth over some of the more nuanced details of acoustic instruments, lending a bold thickness to the sound, rather than a clean and natural quality.

Mids

The balance here is somewhat recessed with not much presence until we hit the upper mids. As in the low-end, the mids have a soft quality with almost a muted resolve. Like chicken soup to the ears, the sound coats the ears with a gentle, smooth and warm liquid. At times, the bass can creep up into the low-mids, again veiling the profile a tad. And in the lower midrange, singular instruments suffer in definition because of this bleed from the bass. However, once we creep up into the higher frequencies, the sound cleans up with added snap to percussion but still an overall softeness and majesty that adds tenderness to the delivery.

Highs

The highs of the Neon 4 exhibit a pleasing fluidity and ease. While there is good detail, the emphasis is on smoothness rather than texture, especially in the presentation of string instruments and vocals. Despite this, the range sounds natural, allowing vocals to shine with an intimate and authentic presence. Still, there is a notable thickness to vocals and other instruments, and it lacks a pronounced sparkle, indeed displaying a touch of roll-off. That being said, this range is abundantly forgiving and relaxed.

Summary

The Neon 4 presents a thick and powerful personality with a massive low-end, smooth highs and a vibrant soundstage. If you have an aversion to big bass, the Neon 4 may be a bit much. In addition, the slight lack of cleanliness in the bass and low-mids may prove problematic to uncompromising audiophiles who expect immaculate separation, especially considering the significant price tag. That being said, the Neon 4 is a ton of fun, and it throws crazy energy into anything from pop to EDM. Certainly, if you love bass and a hedonistically rich flavor in your IEMs, the Neon 4 will give you the fix you need.

You can buy the Fir Audio Neon 4 at Audio 46.