64 Audio U4S vs Thieaudio Valhalla: which should you buy?

On aggregated review scores the Thieaudio Valhalla comes out ahead with a HearWiki score of 81. The full breakdown - sub-scores, specs and what reviewers actually said - is below.

Our pick: Thieaudio Valhalla - Great overall at around $1999.

Wired IEMs

Score breakdown

Each axis is a 0–10 blend of what reviewers scored, not a lab measurement.

Neither pulls ahead overall - they trade wins across the measures.

64 Audio U4S
Thieaudio Valhalla

HearWiki score

Sound

8.5

9.0

Value

7.5

6.0

Price (USD)

$1,100

$2,000

Generation & platform

The scores rank quality. This is the other question: is the newer one actually newer technology, or the same platform in a new shell?

Same generation

The Thieaudio Valhalla is 2 years newer, but it is the same generation of hardware: nothing in the radio, the codecs or the noise cancelling separates them. Nothing separates them on convenience features either, so the choice comes down to tuning and price.

U4S2023
Valhalla20252 yr newer

Specifications

U4SValhalla

Type: Wired IEMs; Wired IEMs
Price (USD): $1,100; $2,000
HearWiki score: 76; 81
Released: 2023; 2025
Availability: Discontinued; Sold new
Driver: 1DD + 3BA hybrid; 19× balanced armature
Driver type: hybrid; balanced-armature
Driver configuration: 1DD + 3BA; -
Drivers per side: 4; 19
Impedance: 11 Ω; 9 Ω
Sensitivity: 107 dB/mW; -
Active noise cancelling: No; No

Specification comparison of 64 Audio U4S vs Thieaudio Valhalla
Spec	64 Audio U4S	Thieaudio Valhalla
Type	Wired IEMs	Wired IEMs
Price (USD)	$1,100	$2,000
HearWiki score	76 / 100 Great	81 / 100 Great
Released	2023	2025
Audio
Driver	1DD + 3BA hybrid	19× balanced armature
Driver type	hybrid	balanced-armature
Driver configuration	1DD + 3BA	-
Drivers per side	4	19
Impedance	11 Ω	9 Ω
Sensitivity	107 dB/mW	-
Features
Active noise cancelling	No	No

What reviewers said

64 Audio U4S

The 64 Audio U4S is a hybrid universal IEM that blends a dynamic driver with three balanced armatures to deliver a well-rounded, musical sound signature. It offers punchy, well-defined bass, smooth mids, and crisp treble, making it a versatile and easy-to-drive choice for a wide range of genres. While its tuning leans toward enjoyment rather than pure neutrality, it maintains solid technical performance with good detail retrieval and soundstage for its price point.

Pro:Energetic and well-extended bass response
Pro:Smooth, natural midrange with good vocal presence
Pro:Easy to drive thanks to high sensitivity and low impedance

Con:Lower mids can sound slightly recessed to some ears
Con:Lacks active noise cancellation for noisy environments
Con:Price point may be high for those seeking a strictly neutral sound

Thieaudio Valhalla

The Thieaudio Valhalla is a premium all-balanced-armature in-ear monitor that prioritizes technical clarity and precise sound staging. Its design focuses on delivering crisp, well-defined bass, transparent mids, and extended treble without harshness, making it a strong choice for analytical listening rather than a relaxed, warm signature. The build quality and fit are top-tier, reflecting its flagship status.

Pro:Exceptional detail retrieval and instrument separation
Pro:Clean, well-controlled bass with solid punch
Pro:Neutral yet engaging tuning across the frequency range

Con:Very high price point limits accessibility
Con:Low impedance may require a quality source to avoid hiss
Con:Not suited for listeners seeking a warm or laid-back sound

Summaries are AI-condensed and paraphrased from published reviews and specs - not original hands-on testing. More on our method.

Compare something else

Swap either side out, or start again from the picker.

New comparison 64 Audio U4S Thieaudio Valhalla