(Last Updated On: November 6, 2020)

Despite being new, FiR Audio rocks the IEMs industry by launching their M-series IEMs, which utilize plenty of useful technologies that help to improve the overall sonic performance.

Thank you, Project Perfection Pte Ltd, the authorized distributor for FiR Audio in Asia region for loaning me the M4 IEMs. It was loaned to me in exchange for my honest review and opinion. The unit will be returned to Project Perfection after this review.

Introduction

FiR Audio is a relatively new IEM manufacturer in the industry. It was founded in 2018 by Bogdan Belonozhko, a longtime IEM pioneer. He was the CEO for the well-known 64Audio. He left the company to his brother, Vitaliy Belonozhko and founded Fir Audio afterwards together with 2 partners, his younger brother Alex Bolonozhko, and a long-time colleague, Daniel.

Initially, FiR Audio produces a variety of necessary and essential accessories such as IEM vacuum tool and IEM cable tester for all IEM owners. In CanJam Singapore 2019, FiR Audio debuted prototypes of their M-series IEMs, from entry-level M2 to the flagship M5. The numerical value at the end of the model indicates the number of drivers in the IEMs.

After receiving the feedback from fellow audio enthusiasts in CanJam, FiR Audio further worked on the tuning and packaging. Soon after, the official version of M-series IEM was launched.

In today’s article, we are going to take a look on the M4 from FiR Audio. Let’s find out more about this maiden work!

FiR Audio M4

FiR Audio M4

"The FiR Audio M4 has a warm and musical sound profile. The overall sonic presentation is lush and rich in texture. The sound signature can be categorized as U-shaped, with the bass and treble getting more emphasis compared to the mids. Don’t get me wrong, the mids are still great - clean, neutral and transparent."

Pros:

  • »Warm and lush sound signature for comfortable listening
  • »Excellent build quality
  • »Accurate and precise bass response
  • »Uncolored and natural midrange for vocal monitoring
  • »High quality stock cable
  • »Smooth and well extended highs
  • »Modern faceplate design

Cons:

  • »Might be bright for those who have lower tolerance to treble
  • »High price
  • »Protruded MMCX design

Unboxing

Unfortunately, the packaging of the FiR Audio M4 was not provided for me when the unit was loaned. So, I will have to skip this section. Here’s the accessories in the box:

  • Warranty card
  • User guide
  • Round sticker
  • Brown round leather case
  • 3 pairs of silicone ear tips
  • 2 pairs of foam ear tips
  • Eight wire braided silver-plated copper (SPC) cable

Technical Specifications

  • Driver configuration: 4-driver hybrid – 10mm dynamic driver for lows, single BA driver for mids, single BA driver for upper mids and single direct treble BA driver
  • Frequency Response: 10 Hz – 20,000 Hz
  • Nominal Impedance: 6.4 Ohms
  • Connection (Universal Fit): MMCX female socket (Gold Plated)
  • Chassis Material (Universal Fit): Sandblasted and anodised aluminum processed with CNC-machined from a single block
  • Colour (Universal Fit): Black body with champagne gold faceplate

Build

FiR Audio utilizes a dual color scheme for the design of M4. The shell body is in black and it matches with a champagne gold faceplate. This color combination made the M4 look classy. On the left faceplate, there is the FiR Audio logo on it while on the right, there is the model name.

The build quality of the M4 is great and I seriously feel that it gives me the premium feeling when I am holding it in my hand. Despite the shell and the faceplate being in two pieces, they are sealed perfectly. No excessive glue stains or gap in between the shell and faceplate.

The faceplate of FiR Audio M4
The faceplate of FiR Audio M4

M4 is equipped with MMCX connectors. Unlike conventional MMCX connectors, which are normally flush on the shell, the gold-plated MMCX connectors on M4 are protruded out from the shell. You can still pair the M4 with after-market cables but the protrusion will not be fully covered by the cable. There are two holes near the MMCX connectors. One of them is for the ATOM module while the other is for driver flex mitigation.

FiR Audio ATOM module also known as the Air Transferring Open Module, is a pressure release system developed by Bogdan Belonozhko following experimentation with a variety of nano-thin membranes and foam materials. FiR’s ATOM has a significantly reduced filter size, allowing its IEMs to be less affected by air volume within the module while allowing for a positive effect on sound presentation, widening the soundstage while helping to alleviate listener fatigue.
The protruded MMCX socket on FiR Audio M4
The protruded MMCX socket on FiR Audio M4
2 vents on each side of FiR Audio M4 for driver flex mitigation and ATOM implementation.
2 vents on each side of FiR Audio M4 for driver flex mitigation and ATOM implementation.

The nozzle is relatively long compared to most of my universal IEMs. This ensures a deep insertion, which is a prerequisite for good isolation. There are two lips on the nozzle. This secures the ear tips to stay on the nozzles and prevents the ear tips from being stuck in your ears.

The long nozzle on FiR Audio M4 with dual lips to provide a better catch to ear tips
The long nozzle on FiR Audio M4 with dual lips to provide a better catch to ear tips
Side view of the angled nozzle
Side view of the angled nozzle
Side view of the angled nozzle
Side view of the angled nozzle

The cable provided in the box is an eight core braided SPC cable. The MMCX connectors of the cable are specially designed to cater to the protruded MMCX sockets on the M4. So, this stock cable cannot be used for other IEM, despite utilizing MMCX. There are heat-shrink ear guides on the cable to ensure a good and stable fitting. The stock cable is 3.5mm unbalanced terminated.

The stock cable provided by FiR Audio
The stock cable provided by FiR Audio
Eight SPC wires are braided neatly
Eight SPC wires are braided neatly
The MMCX connector on the cable is specially designed for the protruded MMCX socket on FiR Audio universal IEMs (UIEMs).
The MMCX connector on the cable is specially designed for the protruded MMCX socket on FiR Audio universal IEMs (UIEMs).
The Y-splitter and chin slider
The Y-splitter and chin slider
the 3.5mm unbalanced TRS jack
the 3.5mm unbalanced TRS jack

Fit and Isolation

As mentioned in the previous section, nozzles of M4 are longer compared to other universal IEMs. It provides a deep insertion to my big and long ear canal. The isolation is above average. I did some ear tip rollings and I ended up pairing it with Sedna EarFit Xelastec. It provides the best isolation result among all the after-market ear tips, such as Final Audio Type-E and SpinFit CP100.

For those who are interested in getting the M4 in custom version, you can choose to have modular vents on your faceplates. By getting the ATOM-X package, the isolation of the IEMs can be changed according to the ATOM module used. For universal M4, it comes with FiR’s N Isolation ATOM module, which lowers the isolation to -15dB.

FiR Audio M4 with Sedna Earfit Xelastec
FiR Audio M4 with Sedna Earfit Xelastec
FiR Audio M4 with Sedna Earfit Xelastec
FiR Audio M4 with Sedna Earfit Xelastec

Sound Analysis

To analyze the sonic performance of the M4, I paired it with my Lotoo PAW 6000. Rated at 6.4 ohms for impedance, the M4 is a pair of efficient IEMs which can be easily driven by most of the DAPs in the market. However, it will be more advantageous if you paired it with a more powerful source because the 10mm dynamic driver does need a certain amount of power to unleash the full potential.

FiR Audio M4 on Lotoo PAW 6000
FiR Audio M4 on Lotoo PAW 6000

Sound signature and soundstage

The FiR Audio M4 has a warm and musical sound profile. The overall sonic presentation is lush and rich in texture. The sound signature can be categorized as U-shaped, with the bass and treble getting more emphasis compared to the mids. Don’t get me wrong, the mids are still great – clean, neutral and transparent.

Soundstage wise, the M4 has a wide headroom. The headroom or soundstage is highly dependent on the source. I tried it with Astell & Kern SR15, the headroom is slightly two-dimensional as compared to the three-dimensional stage on my Lotoo PAW 6000. This further strengthens my finding of a powerful source will be more advantageous to M4 in terms of sonic performance.

FiR Audio M4 with Lotoo PAW 6000
FiR Audio M4 with Lotoo PAW 6000

Lows

Powered by a 10mm dynamic driver, the bass is energetic, fast and impactful. I like how M4 delivers the bass instruments, they are realistic and accurate. It has good sub-bass extension. This creates a three-dimensional stage for better layering and separation between instruments and vocals.

The speed of the bass is faster than conventional big dynamic drivers. It maintains the tidiness and cleanliness of the presentation. Despite being fast, the rich and full bodied bass introduces a good amount of warmth into the profile, making M4 comfortable to listen to. Due to the warmth, I don’t feel any fatigueness while listening for a long period of time.

The mid bass of the M4 is more conservative compared to the sub-bass. It still has the same profile of the sub-bass – rich and full bodied. This makes the transition smooth without any awkward gaps in between. The positioning of the mid-bass starts to be slightly recessed as compared to the sub-bass. This further enhances the accuracy and precision of the overall bass performance.

FiR Audio M4
FiR Audio M4

Mids

As mentioned in the analysis on the overall sound signature, the mids delivered by M4 is slightly recessed, as compared to the bass and treble. Despite being recessed, the mids still preserve the highest quality. It has minimum coloration; in a simpler term – transparent. The warmth of the bass does not cause the mids to be overly smoothened or colored. The original flavors are still well preserved.

The layering between the mids and lows have been well-handled by the M4. The lower mids exhibit warmth from the lows. Listening to male vocals like Taiwanese singer Jay Chou, the presentation is rigid and penetrating. Due to the warmth and lushness from the lows, the flow is smooth and emotional. There is no dryness observed in the presentation.

Transitioning to the upper mids, the profile becomes more neutral, with the warmth starts to reduce. The presentation becomes more airy and spacious. This is the spotlight of M4. Female vocals are well-presented by the M4. Jennifer Warnes and Adele sound silky sweet. With the spaciousness in the upper mids, the notes are flowing freely without congestions or collisions.

FiR Audio M4
FiR Audio M4

Highs

The highs are handled by a direct treble BA driver. What is a direct treble BA driver?

FiR Audio’s Direct Treble driver removed the spout, which is conventionally found in classic BA driver designs. The spout prevents sound from expanding naturally, resulting in muffling or even distortion. By removing the spout, it widens the aperture on the driver and allows more air through—negating any harshness or muffling and resulting in a more natural, organic sound.

The Direct Treble driver in M4 harmonises with the other drivers within the chassis, giving the M4 a natural, organic signature as compared to its counterparts. With this implementation, the highs are well extended. The extension is better compared with most of my IEMs with conventional BA drivers. It’s as good as electrostatic or magnetostatic driver handled highs.

The distortion in the highs is bare minimum, resulting in a clean and neat overall presentation. Due to this, the overall clarity of M4 is outstanding. This technology is indeed a breakthrough and the bottleneck of conventional BA drivers handling treble is solved.

FiR Audio M4
FiR Audio M4
FiR Audio M4
FiR Audio M4

Verdict

Being the maiden work of FiR Audio, I am really satisfied with this outstanding performance, on both physical and sonic levels. The build quality of the M series is classy and modern. For those who prefer custom IEMs (CIEMs), pay attention to FiR Audio custom builder on their website. The degree of freedom in customizing is extremely high and the platform is user-friendly.

There are plenty of great technologies implemented in the M-series to help further enhance the overall performance. I am glad to see the combination of art and science in this masterpiece. I totally agree with the saying that science helps to improve quality of life by listening to FiR Audio M4. It’s that great!

FiR Audio M4 is retailing at USD$1899. You can purchase it from Project Perfection Official Website or FiR Audio Official Store.

With the launch of M-series, especially M4, FiR Audio successfully shows to the world that bottleneck on conventional design in IEMs can be breakthrough and overcome, by implementing the right technologies. The game is changed and a new benchmark is established! Well done, FiR Audio!

FiR Audio M4
FiR Audio M4