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A Rising Hi-Fi Brand’s New Audiophile Headphones Are More Affordable Than You’d Expect

Best know for its affordable amps, the brand continues its expansion into more traditional hi-fi.

Close-up of a silver metallic device with a perforated orange grille and two gold connectors on top.Fosi Audio

By Tucker Bowe

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Fosi Audio continues to be a rising force in the budget hi-fi market. While best known for its affordable desktop amplifiers, the brand has recently expanded into more traditional hi-fi.

In the last several months, for example, Fosi Audio has introduced its first over-ear headphones, i5 ($550), as well as its first turntable, the Luna3 ($349). And now it is continuing the trend with the IM4, its first pair of in-ear monitors.

Fosi Audio IM4

Fosi Audio IM4 in-ear monitors
The IM4s are Fosi Audio’s first in-ear monitors.
Fosi Audio

Fosi Audio’s IM4s are in-ear monitors aimed at burgeoning audiophiles. They have an open-back design that, similar to open-back headphones, promises to deliver a natural sound with a wider soundstage compared to most (closed-back) in-ear monitors.

And, because of their open-back design, these IM4 in-ear monitors are intended for use in quiet spaces — not only will outside sounds interfere with your music, but others will also be able to hear what you’re listening to.

Pair of black in-ear monitors with red mesh accents on a reflective black surface.
Each earpiece has a unique open-back design that, similar to open-back headphones, promises to deliver a more spacious sound.
Fosi Audio

Open-back, beryllium

At the heart of each IM4 earbud is a 10mm beryllium-coated diaphragm driver. It’s then paired with an N52 dual-magnet system and dual-chamber acoustic design.

According to the brand, this combination of components helps deliver “smooth highs, detailed mids, and deep, controlled bass with a natural balance suited for music, movies, gaming, and streaming.”

Silver and black in-ear monitor earphone with a braided silver cable on a black reflective surface.
Each IM4 earbud (in silver here) has a lightweight design, weighing just 7 grams.
Fosi Audio

The IM4 earbuds were made with comfort in mind, too. Each earpiece is CNC-machined from aluminum and weighs just 7 grams. And they promise to have a secure, but pressure-free fit that should make them comfortable enough for multi-hour listening sessions.

Silver metallic earphone shell with black and gold small cylindrical components on a reflective black surface.
The earbuds have swappable aluminum and brass nozzles, which allow you to customize your sound.
Fosi Audio

Customizable sound and hardware

Maybe most interestingly, each earpiece comes with swappable aluminum and brass nozzles that allow you to tweak the sound signature — Fosi Audio the tuning can be adjusted for “smoother highs to more energetic bass and treble.”

Silver braided audio cable with a 3.5mm gold-plated connector and red and blue pin connectors on a black reflective surface.
The detachable cables are compatible with 3.5mm and 4.4mm sources.
Fosi Audio

Additionally, the IM4s come with detachable cables that have connections for both 3.5mm and 4.4mm jacks, meaning they can work with a wide range of devices.

Two pairs of wireless earbuds, one black and one silver, each with translucent silicone ear tips, placed on a dark surface.
The two colors options: black (left) and silver (right).
Fosi Audio

Price and availability

The Fosi Audio IM4 in-ear monitors come in two different finishes, black or silver, and are priced at $100. This price point places them as one of the more affordable IEMs on the market.

As for buying them, it’s not as straightforward as you might hope. Fosi Audio has launched them as a Kickstarter campaign; however, it has already far exceeded its funding goal.

According to the page, the brand has an “November 2025” ship date for its earliest backers.

About the Author:

Tucker Bowe has been on Gear Patrol’s editorial team since 2014. As a Tech Staff Writer, he tracks everything in the consumer tech space, from headphones to smartphones, wearables to home theater systems. If it lights up or makes noise, he probably covers it.

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