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Fosi Audio’s $100 IEMs Could Be the Budget Audiophile Breakthrough of 2025

Fosi Audio steps deeper into high-fidelity with its first in-ear monitors — and they might surprise you.


Silver device with a white symbol and orange perforated texture on a black background. Two small gold connectors at the top.

From Budget Amps to Full-Fledged Hi-Fi


If you’ve been paying attention to the hi-fi scene over the past few years, you’ve probably noticed Fosi Audio popping up again and again. Once known primarily for its affordable desktop amplifiers, the brand has quietly become a favorite among music lovers seeking great sound without the steep price tag.


Now, Fosi is taking things up a notch. After launching its first over-ear headphones (the i5, $550) and even a turntable (the Luna3, $349), the company is expanding further into traditional hi-fi territory.


Its latest creation? The IM4 — Fosi Audio’s very first pair of in-ear monitors (IEMs).





Meet the Fosi Audio IM4


Designed for budding audiophiles, the Fosi Audio IM4 IEMs promise open-back headphone sound in a compact, in-ear design.


That’s a rare feat. Open-back construction, usually found in high-end over-ear headphones, gives sound more space, air, and natural resonance, creating a listening experience that feels less “in your head” and more like sitting in a real room with live instruments.


Of course, the tradeoff is that these are best suited for quiet environments — because you’ll hear the world, and the world will hear you.


Still, for those who crave realism and soundstage over isolation, this design choice makes the IM4s something special in their price range.


Silver earphones with braided cables on a black background, featuring small red decorative elements and a sleek modern design.

Open-Back, Beryllium Brilliance


Under the hood, each IM4 earbud features a 10mm beryllium-coated diaphragm driver, paired with an N52 dual-magnet system and a dual-chamber acoustic design.

This trio of engineering choices aims to produce a sound signature that’s balanced, dynamic, and rich in texture — with smooth highs, clear mids, and deep, controlled bass.

Fosi says the result is a natural tonality that flatters all kinds of content — whether you’re streaming high-res music, gaming, or watching films with intricate sound design.


Comfort Meets Craftsmanship


Each IM4 earpiece is CNC-machined from aluminum, giving it both strength and style while keeping weight to a mere 7 grams per earbud.


That lightweight build, combined with a pressure-free ergonomic fit, means the IM4s are made for long, fatigue-free listening sessions. Whether you’re in the studio or at your desk, these IEMs are built to disappear — leaving only the sound.




Customize Your Sound


Perhaps the IM4’s most intriguing feature is its swappable nozzle system. Each pair includes aluminum and brass nozzles that subtly alter the sound signature — allowing listeners to choose between smoother highs or more energetic bass and treble.


This kind of tuning flexibility is something usually reserved for IEMs that cost many times more. It’s a welcome addition that lets you tailor the sound to your personal taste or even to different genres.


Black earbuds with metallic finish and orange highlights, placed on a reflective black surface, creating a sleek and modern look.

Built for Modern Audiophiles


The detachable braided cables connect via standard 2-pin connectors and come with 3.5mm and 4.4mm terminations, ensuring compatibility with everything from smartphones and laptops to dedicated DACs and balanced amplifiers.


Whether you’re running them off a portable DAC or your desktop setup, the IM4s are designed to scale with your gear.


Style Options


Fosi keeps it simple and refined: the IM4s are available in two finishes — silver or black. Both versions share the same sleek metallic chassis and subtle industrial aesthetic that has become a Fosi hallmark.



Price and Availability


The Fosi Audio IM4 in-ear monitors are priced at just $100 — placing them firmly in the budget audiophile tier, but with features that hint at a much more premium lineage.

They’ve launched via Kickstarter, and as of early October, the campaign has already blown past its funding goal. Early backers are expected to receive their units in November 2025.

Given Fosi’s proven track record with affordable amps and DACs, expectations for the IM4 are understandably high.


Silver earphones with twisted cables lie on a dark surface. A black audio device with an orange knob is blurred in the background.

Fosi Audio IM4 — Key Specs


Feature

Specification

Driver

10mm beryllium-coated diaphragm

Magnet System

N52 dual-magnet

Acoustic Design

Dual-chamber, open-back

Weight

7 grams per earbud

Tuning Options

Swappable aluminum and brass nozzles

Cable

Detachable 2-pin with 3.5mm & 4.4mm connectors

Finishes

Black or Silver

Price

$100

Availability

Kickstarter (shipping Nov 2025)


Final Thoughts


Fosi Audio has built a reputation by delivering real hi-fi performance at unreal prices, and the IM4 looks like the next logical step in that evolution.


With its open-back design, customizable tuning, and thoughtful engineering, the IM4 isn’t just another budget IEM — it’s a statement that audiophile sound doesn’t have to come with an audiophile price tag.


If the brand’s recent track record is any indication, these might just become the best $100 in-ear monitors of the year.



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