64 Audio U4S VS Campfire Audio Alien Brain

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

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64 Audio U4S and Campfire Audio Alien Brain use 1DD+3BA and 1DD+4BA driver setups respectively. 64 Audio U4S costs $1,100 while Campfire Audio Alien Brain costs $1,000. 64 Audio U4S is $100 more expensive. Campfire Audio Alien Brain holds a slight 0.1-point edge in reviewer scores (8.1 vs 8.3). 64 Audio U4S has slightly better mids with a 0.3-point edge, Campfire Audio Alien Brain has better treble with a 0.9-point edge, Campfire Audio Alien Brain has slightly better dynamics with a 0.3-point edge, Campfire Audio Alien Brain has significantly better soundstage with a 2-point edge, 64 Audio U4S has slightly better details with a 0.3-point edge and 64 Audio U4S has better imaging with a 0.5-point edge.

Insights

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

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

Campfire Audio Alien Brain Aggregated Review Score

Average Reviewer Scores

Smirk Audio
Jaytiss Head-Fi.org

Average Reviewer Score:

8.3

Very Positive

Reviews Comparison

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+

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Price: $1,122

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Campfire Audio Alien Brain reviewed by Smirk Audio

Smirk Audio 7.5 Reviewer Score
A Tuning
A- Tech
check links for more info:

Smirk Audio original ranking

Smirk Audio Head-Fi Profile

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

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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

Campfire Audio Alien Brain reviewed by Jaytiss

Jaytiss 8.8 Reviewer Score
A Tuning
A+ Tech
YouTube video thumbnail
So simple and nice it's hard to not love.
Youtube Video Summary

Alien Brain arrives as a single-DD + 4BA hybrid around $1,000 with a truly peculiar shell: the rounded, “alien cortex” faceplate is magnetic, uses MMCX, and can be tricky to seat. The unboxing is lavish—two cables (including 4.4 mm), a compact magnetic leather case, a USB-C DAC/amp, foams plus “sticky” tips, cleaning tools, and extras. Fit is the hurdle; tip-rolling is essential, but once positioned correctly, comfort and seal fall into place.

Tonally, this set pursues a balanced, all-rounder tuning with a near-ideal bass shelf, lively but controlled upper mids, and sparkly yet composed treble. There’s punch and detail without drifting into fatigue; extension is strong, but staging isn’t the most expansive and note weight isn’t “thumpy”—this isn’t a bass-head cannon, more a clean, grounded presentation. The FR shows a touch of 1 kHz energy and smooth ripples through presence/air that favor natural timbre over hyper-etched brilliance, making it a long-session, non-fatiguing listen.

Versus Campfire’s own lineup, it’s far more normalized than the colorful Trifecta, better extended than the warm Axion, and closer in poise to Moon Rover but with a bit more bass and refinement. Compared to peers like Dunu Glacier or DA Mecca, Alien Brain trades V-shaped excitement for cohesive neutrality, and avoids the upper-mid glare that can scare off listeners. Net result: a strong recommendation for those who can manage the fit and want a high-end Campfire that does something new—not the classic house warmth, not sterile flatness, but a realistic, well-rounded signature with broad appeal.

Mids: A- Treble: A+ Dynamics: A+ Soundstage: A+

Jaytiss original ranking

Jaytiss 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

Campfire Audio Alien Brain reviewed by Head-Fi.org

Head-Fi.org 8.5 * score rescaled + normalized
4 community members have rated the Campfire Audio Alien Brain at an average of 4.5/5 on Head-Fi. Overall sentiment: Outstanding.

URL to full Review

Head-Fi.org original ranking

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

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 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 User Review Score

Average User Scores

Average User Score: n/a

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Campfire Audio Alien Brain User Review Score

Average User Scores

Average User Score: n/a

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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

Campfire Audio Alien Brain Gaming Score

Gaming Score & Grade

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

Gaming Score

6.7

Gaming Grade

B+

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

Campfire Audio Alien Brain Scorings

Average Technical & Tuning Grades

Average Tunign Grade

A
  • The response is even and composed, lending itself to effortless genre hopping. Voices sit comfortably in the mix.

Average Technical Grade

A
  • The balance of resolution and space feels assured, keeping complex passages coherent. Layering is convincing on most studio mixes.
Bass A+
It delivers flagship-worthy bass, rich in both rumble and nuance. Reference tracks showcase its grip.
Mids A
The mids sound lush and articulate, capturing emotion effortlessly. Strings and keys shimmer with realism.
Treble A
The treble is exquisitely tuned, combining crystal detail with relaxed delivery. Micro-details emerge effortlessly.
Dynamics A+
The presentation feels expansive, letting micro and macro dynamics breathe. There's a sense of limitless headroom.
Soundstage A+
Immersive holography surrounds the listener, making the venue feel tangible and enveloping. It delivers a grand, cinematic presentation.
Details A-
Micro-details glide to the forefront effortlessly while timbre remains natural. Ambient cues are vivid and lifelike.
Imaging A-
You can literally point to where sounds originate across the stage. You can point to where sounds originate.
Gaming B+
Respectable environmental presentation favors atmosphere over precision. Detects obvious directional cues while conveying game world ambiance. Bad value-to-cost for gaming purpose - not recommended

64 Audio U4S User Reviews

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Campfire Audio Alien Brain User Reviews

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