Fearless ACME8 VS 64 Audio U4S

IEM Comparison: Expert & Community Scores Side-by-Side

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Fearless ACME8 and 64 Audio U4S use 8BA and 1DD+3BA driver setups respectively. Fearless ACME8 costs $1,100 while 64 Audio U4S costs $1,100. 64 Audio U4S holds a decisive 5.6-point edge in reviewer scores (2.5 vs 8.1).

Insights

Metric Fearless ACME8 64 Audio U4S
Bass 2.5 8
Mids 2.5 7.8
Treble 2.5 6.8
Details 2.5 7.3
Soundstage 2.5 6
Imaging 2.5 7.5
Dynamics 2.5 7.7
Tonality 2.5 7.4
Technicalities 3 7
Take these comparisons with a grain of salt—we don't have enough Fearless ACME8 reviews saved yet to provide an unbiased result.

Fearless ACME8 Aggregated Review Score

Average Reviewer Scores

Crin

Average Reviewer Score:

2.5

Very Negative

64 Audio U4S Aggregated Review Score

Average Reviewer Scores

Smirk Audio Jaytiss Precogvision
Audionotions Head-Fi.org
Super* Review

Average Reviewer Score:

8.1

Very Positive

Reviews Comparison

Fearless ACME8 (more reviews)

Fearless ACME8 reviewed by Crin

Crin 2.5 Reviewer Score
D- Tuning
D Tech
Weird and bloaty bass in conjunction with tonally weird midrange.

Crin original ranking

Crin Youtube Channel

64 Audio U4S (more reviews)

64 Audio U4S reviewed by Super* Review

Super* Review 9* * score rescaled + normalized
YouTube video thumbnail
Youtube Video Summary

The 64 Audio U4s hits a compelling sweet spot: a 1DD+3BA hybrid around $1,100 that echoes the lush, bass-tilted character of the Nio while fixing key drawbacks. Packaging and accessories feel improved, with multiple tip options and the included M12 APEX module; APEX not only tailors bass but also relieves pressure for long sessions. Fit follows 64 Audio’s comfortable triangular shell; the vented DD asks for a slightly shallower insert than the all-BA models. Sonically, expect a sub-bass-oriented shelf and a treble profile that’s more lively and “zingy” than the Nio, with extra energy around the upper treble. The big caveat is 64 Audio’s muted 2–4 kHz region, which can set soprano vocals a step back on the stage.

Against the brand’s full-BA staples (think U12t/U6t), the U4s trades some pinpoint imaging and coherency for unmistakable DD slam and tactile “air pushing.” Extension at both ends is excellent, with upper-treble energy that makes micro-detail and reverb trails pop. It’s not the clean, conventional neutrality of something like a Monarch-style tuning; rather, it’s a deliberate, colored signature that delivers fun plus technical chops. Crucially, it fills a missing niche at its price and, in many respects, outperforms the pricier Nio, making the U4s a standout recommendation for listeners who want bass authority, sparkle, and engaging dynamics without going all-in on the flagship tier.

Super* Review original ranking

Super* Review Youtube Channel

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64 Audio U4S reviewed by Audionotions

Audionotions 8.5 Reviewer Score
A step down in techs from U12T (possibly a half step down from U6T). But very well tuned and adds in a dynamic driver punch. Timbre is slightly improved compared to U12T due to the increase in midbass and upper mids energy. On the second hand market, 64Audio IEMs are among the best values in portable audio, the U4S is no exception.

Audionotions original ranking

Website (Audionotions)

64 Audio U4S reviewed by Smirk Audio

Smirk Audio 7.8 Reviewer Score
A Tuning
A Tech
A tastefully colored U12t with a more intimate soundstage, a cutback in technicalities, and more bass realism.

Smirk Audio original ranking

Smirk Audio Head-Fi Profile

Bass: A+ Mids: A Treble: A Dynamics: A+ Details: A Imaging: A+

64 Audio U4S reviewed by Jaytiss

Jaytiss 7.8 Reviewer Score
B+ Tuning
B Tech
It's a solid set, with great build quality, but sonically isn't the specialist that I want it to be.

Jaytiss original ranking

Jaytiss Youtube Channel
Mids: A+ Treble: B Dynamics: A- Soundstage: B

64 Audio U4S reviewed by Precogvision

Precogvision 7.7 Reviewer Score
A Tuning
A- Tech
YouTube video thumbnail
Fantastic colored tonality with options, and the unique technical qualities to back it up. M12/M15 modules recommended.
Youtube Video Summary

The 64 Audio U4s hits a compelling sweet spot: a 1DD+3BA hybrid around $1,100 that echoes the lush, bass-tilted character of the Nio while fixing key drawbacks. Packaging and accessories feel improved, with multiple tip options and the included M12 APEX module; APEX not only tailors bass but also relieves pressure for long sessions. Fit follows 64 Audio’s comfortable triangular shell; the vented DD asks for a slightly shallower insert than the all-BA models. Sonically, expect a sub-bass-oriented shelf and a treble profile that’s more lively and “zingy” than the Nio, with extra energy around the upper treble. The big caveat is 64 Audio’s muted 2–4 kHz region, which can set soprano vocals a step back on the stage.

Against the brand’s full-BA staples (think U12t/U6t), the U4s trades some pinpoint imaging and coherency for unmistakable DD slam and tactile “air pushing.” Extension at both ends is excellent, with upper-treble energy that makes micro-detail and reverb trails pop. It’s not the clean, conventional neutrality of something like a Monarch-style tuning; rather, it’s a deliberate, colored signature that delivers fun plus technical chops. Crucially, it fills a missing niche at its price and, in many respects, outperforms the pricier Nio, making the U4s a standout recommendation for listeners who want bass authority, sparkle, and engaging dynamics without going all-in on the flagship tier.

Bass: A+ Mids: A+ Treble: A- Dynamics: A+ Details: A- Imaging: A-

Precogvision original ranking

Precogvision Youtube Channel

64 Audio U4S reviewed by Head-Fi.org

Head-Fi.org 8 * score rescaled + normalized
4 community members have rated the 64 Audio U4s at an average of 4.3/5 on Head-Fi. Overall sentiment: Excellent.

URL to full Review

Head-Fi.org original ranking

Fearless ACME8 User Review Score

Average User Scores

Average User Score: n/a

Based on 0 user reviews

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64 Audio U4S User Review Score

Average User Scores

Average User Score: n/a

Based on 0 user reviews

No user reviews yet. Be the first one who writes a review!

Fearless ACME8 Gaming Score

Gaming Score & Grade

  • The gaming score is prioritizing technical capabilities of the IEM (Separation, Layering, Soundstage) and good value.

Gaming Score

1.9

Gaming Grade

E

64 Audio U4S Gaming Score

Gaming Score & Grade

  • The gaming score is prioritizing technical capabilities of the IEM (Separation, Layering, Soundstage) and good value.

Gaming Score

6.1

Gaming Grade

B

Fearless ACME8 Scorings

Average Technical & Tuning Grades

Average Tunign Grade

D-
  • Balance is severely off, producing a harsh, unpleasant listen regardless of genre. Long sessions quickly become exhausting.

Average Technical Grade

D
  • Details smear quickly, leaving the presentation cramped and low on definition. You'll notice smearing on even moderately layered songs.
Gaming E
Compromised imaging significantly impacts gameplay awareness. Directional cues often lack accuracy or consistency. Bad value-to-cost for gaming purpose - not recommended

64 Audio U4S Scorings

Average Technical & Tuning Grades

Average Tunign Grade

A-
  • A smooth, agreeable balance keeps the presentation engaging without obvious flaws. Only sensitive ears will nitpick the bumps.

Average Technical Grade

A-
  • Technical chops are reliable, pairing tidy separation with a soundstage that stays conservative. Micro-detail is decent, though never spotlighted.
Bass A+
Expect a gripping low-end presence that marries clarity with visceral impact. Dynamic swings land with thrilling force.
Mids A
Midrange performance is excellent, with natural timbre and great detail. Vocals feel lifelike and full-bodied.
Treble B+
Expect crisp, well-balanced treble that keeps shimmer intact. You hear reverbs decay naturally.
Dynamics A
You get outstanding dynamic agility, from subtle nuances to big hits. Impact comes with quick recovery.
Soundstage B
Good soundstage with proper width and depth, placing instruments in clearly defined positions. Instruments sit in their own lanes.
Details A-
Resolution feels both high and relaxed, capturing nuance with ease. There's zero smearing even at high volume.
Imaging A
Depth mapping feels natural and accurate, supporting convincing immersion. Depth mapping feels precise and natural.
Gaming B
Decent spatial awareness for fundamental positioning. Creates satisfying atmosphere in story-driven games while handling basic directional cues. Bad value-to-cost for gaming purpose - not recommended

Fearless ACME8 User Reviews

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64 Audio U4S User Reviews

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