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Fosi Audio IM4

72/ 100
Great
HearWiki score

Priced about right

$100
typical price, USD
Sold new
Manufacturer pageBuy now onAmazon

At a glance

Brand
Fosi Audio
Type
Wired IEMs
Fit
-
Connection
Wired
Noise cancelling
No
Released
2025

Score breakdowngreat overall

Sound7.4
Value7.8

An open-back wired IEM with a 10 mm beryllium dynamic driver in a dual-magnet, dual-chamber design. It is aimed at everyday and extended listening, with lightweight housings and a relaxed presentation.

The HearWiki takeAI-condensed

The Fosi Audio IM4 is a wired, dual-dynamic-driver IEM around the $100 mark that leans into an open, detailed sound with a focus on upper mids and treble. It's a comfortable, well-built option that shines with vocals and acoustic material, though its tuning may feel a bit uneven for those wanting a perfectly neutral all-rounder. Overall, it offers strong technical performance and value for its price, with a few tonal quirks to consider.

What works

  • Spacious, open soundstage with good separation
  • Comfortable and solid build quality
  • Strong detail retrieval for the price
  • Engaging, musical tuning for vocals and acoustics

What doesn't

  • Tonal balance can feel uneven, especially in lower mids
  • Cymbal timbre can come across as metallic at times
  • No modular plug system included
  • Overall character may sound slightly papery to some listeners

Paraphrased from published reviews & specs - not an original hands-on test. Our AI disclosure.

Specifications

Audio - Fosi Audio IM4
Driver2× 10 mm dynamic
Driver typedynamic
Drivers per side2
Impedance21 Ω

What the reviews said

6 source(s) feeding this product's score.

pragmaticaudio.com

80

The IM4 is described as a comfortable, well-built, and enjoyable open-sounding IEM with strong value for money. The reviewer recommends it for listeners who want an engaging, spacious sound rather than maximum neutrality.

Read the full review

primeaudio.org

80

The IM4 is judged a solid debut from Fosi Audio, with good build quality, a musical tuning, and respectable soundstage/positional cues. The review also notes some shortcomings, including occasional metallic cymbal timbre and the lack of a modular plug system.

Read the full review

soundphilereview.com

75

The IM4 is presented as a niche-tuned IEM that prioritizes upper mids, treble, detail, and separation. The reviewer sees it as a good fit for acoustic and vocal-focused listening, but less convincing as an all-purpose set because the presentation can feel uneven.

Read the full review

headphoneer.com

The IM4 is portrayed as a well-tuned, technically capable IEM that offers excellent value and a spacious, balanced presentation. The review highlights its warm, dry timbre as a distinctive trait and praises its overall performance as an all-rounder.

Read the full review

homestudiobasics.com

The IM4 is characterized as a budget IEM with strong resolution and an attractive design, though it has some tonal imbalance in the lower mids and a slightly papery overall character. Despite those caveats, the reviewer treats it as an easy recommendation at its price.

Read the full review

What YouTube reviewers say

Video reviews we found, each condensed to its verdict. They do feed the HearWiki score, at a measured weight below what a published written review carries.

The consensus

Positiveacross 6 videos

Reviewers largely agree that the Fosi Audio IM4 offers a wide, open soundstage, comfortable fit, and versatile tuning options via interchangeable nozzles and ear tips, making it a strong value around $80–100.

Reviewers liked

  • Wide, open soundstage with good instrument separation
  • Comfortable, lightweight metal build
  • Versatile tuning via interchangeable nozzles and ear tips
  • Good value with included accessories

Reviewers flagged

  • Poor ambient noise isolation due to open-back design
  • Bass may be lean or lack sub-bass for some listeners
  • Bright or upper-mid-forward tuning can be fatiguing
  • No quarter-inch or balanced adapter included
7:08

Open Back In-Ears! : Fosi Audio IM4

Gamesky16.4K viewsOct 2025

The reviewer was impressed with the Fosi Audio IM4 open-back in-ear monitors, praising their spacious soundstage, detailed mids and treble, and tight bass. They found the design and included accessories (nozzles, ear tips, case) to be good value at the early bird price of $80, though they noted bass may not satisfy bassheads and a quarter-inch adapter is missing. Overall, they see it as a unique and worthwhile product.

6:45

A new $100 FAVORITE OPEN BACK | Fosi Audio IM4 OPEN BACK IEM Headset Review

BiboyHaranero15.5K viewsDec 2025

The reviewer highly recommends the Fosi Audio IM4 as an excellent value open-back IEM around $100, praising its comfortable fit, versatile tuning options via ear tips and nozzles, and engaging V-shaped sound with wide soundstage and good instrument separation. It excels for media consumption, gaming, and rock music, though it is not suited for professional monitoring due to coloration.

8:35

Fosi Audio IM4 - Wide Open Sound! and Versatile Too!

AndyAudioVault7.3K viewsOct 2025

The reviewer praises the Fosi Audio IM4 as an impressive and versatile open-back IEM, highlighting its comfortable metal build, easy drivability, and excellent scaling with better sources. They note that the sound can be tailored via interchangeable nozzles and ear tips, with the brass nozzle offering a brighter, more neutral sound and the black nozzle providing a warmer, bassier response. The main drawbacks are poor ambient noise isolation due to the open-back design and a less precise spatial imaging, making it less suitable for gaming or movies.

4:03

Fosi Audio's FIRST IEM is Amazing! IM4 Review

TheHopelessGeek6.5K viewsDec 2025

The reviewer finds the Fosi Audio IM4 to be an impressive first IEM from the company, praising its lightweight build, comfortable design, and well-executed V-shaped tuning. They particularly appreciate the modular nozzle system, noting the brass filter significantly improves treble clarity, and recommend it as a strong option under $100 despite minor quibbles with the default tuning.

10:22

Fosi Audio IM4. Explained simply.

Dracomies5.8K viewsFeb 2026

The reviewer finds the Fosi Audio IM4 to be a beautiful, warm-tilted U-shaped IEM with excellent female vocals and good male vocals, though bass is lean and sibilance can get spicy at high volumes. Overall, it's a highly recommended, easy-to-sell IEM that sounds similar to the Civa Q but with better aesthetics and comfort.

14:41

FOSI AUDIO IM4 REVIEW

Audio-In Reviews5.7K viewsFeb 2026

The reviewer finds the Fosi Audio IM4 to be a well-built and comfortable IEM with a solid accessory package for $100, but notes that its tuning is more upper-mid-forward than he prefers. He recommends using the black nozzles over the brass ones, as the latter can be fatiguing, and concludes that while it's a good set, it doesn't quite match his personal preferences compared to competitors like the Unicom or Defiant.

Summaries are AI condensations of each video's own conclusion, not transcripts. Titles, thumbnails and view counts belong to their channels.

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