Thieaudio Monarch Mk2 VS 64 Audio U4S

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

Thieaudio Monarch Mk2 and 64 Audio U4S use 1DD+6BA+2EST and 1DD+3BA driver setups respectively. Thieaudio Monarch Mk2 costs $1,000 while 64 Audio U4S costs $1,100. 64 Audio U4S is $100 more expensive. Thieaudio Monarch Mk2 holds a clear 0.7-point edge in reviewer scores (8.5 vs 7.8). Thieaudio Monarch Mk2 carries a user score of 8.5. Thieaudio Monarch Mk2 has significantly better treble with a 2-point edge, 64 Audio U4S has significantly better dynamics with a 1-point edge and Thieaudio Monarch Mk2 has significantly better soundstage with a 2-point edge.

Insights

Jaytiss Score
Thieaudio Monarch Mk2
8.5 /10
Jaytiss Score
64 Audio U4S
7.8 /10
Score gap: 0.8
Metric Thieaudio Monarch Mk2 64 Audio U4S
Mids 8 8
Treble 8 6
Soundstage 8 6
Dynamics 6 7
Tonality 7.5 6.8
Technicalities 8 6
Take these comparisons with a grain of salt—we don't have enough Thieaudio Monarch Mk2 and 64 Audio U4S reviews saved yet to provide an unbiased result.

Jaytiss Reviews Comparison

Thieaudio Monarch Mk2 reviewed by

Jaytiss 8.5 Reviewer Score
A Tuning
A+ Tech
Too much unit variation to recommend to others highly.
Youtube Video Summary

Build & accessories: Compact shell with a slightly old-school shape and flat 2-pin connectors, secure fit, and a nozzle some may find a bit much. The package includes Thieaudio’s large, sturdy case, multiple tips, a cleaning brush, and a fabric-sheathed stock cable with a solid chin slider and a durable Y-split. The cable’s modular plug system (2.5/3.5/4.4) locks in confidently and feels well made.

Sound: a neutral foundation with a dash of fun—clean upper mids, tasteful sparkle, and tight, articulate bass. Unit variance shows on graphs (his sample reads a bit bassier with slightly more treble vs other measurements), but the core tuning stays intact: rich mids, smooth presence, and airy extension that present music as natural, wide, and open. Versus Monarch MKIII, this MKII feels less bright and less fatiguing, with fuller mids. Compared to Annihilator 2023, MKII is flatter and more even (Annihilator hits harder and has a 10k zing some hear as “fake”). Against Lime Ears Tera, MKII is a touch warmer and easier; versus the pricier Europa, it tracks similarly on paper but wins on comfort and value; and it offers more body than budget darlings like Hexa, which can come off lean.

Verdict: a high-tier all-rounder prized for midrange timbre, air/detail, note weight, and imaging. It reads neutral-natural with just enough excitement to stay engaging over long sessions. Personal taste and fit still matter—always demo if possible—but within this preference space, Monarch MKII remains a special, well-balanced choice that continues to earn its spot among top IEMs.

Mids: A+ Treble: A+ Dynamics: B Soundstage: A+

Jaytiss original ranking

Jaytiss Youtube Channel
Ad
Using this affiliate link for ordering your Thieaudio Monarch Mk2 or any other IEM helps fund our free service at no extra cost to you.

Price: $999

Buy Thieaudio Monarch Mk2 on Linsoul

64 Audio U4S reviewed by

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

Thieaudio Monarch Mk2 Details

Driver Configuration: 1DD+6BA+2EST

Tuning Type: Neutral with Bass Boost

Brand: ThieAudio Top ThieAudio IEMs

Price (Msrp): $1,000

Support our free service! Buying through our affiliate links costs you nothing extra:

64 Audio U4S Details

Driver Configuration: 1DD+3BA

Tuning Type: Neutral, Neutral with Bass Boost

Brand: 64 Audio Top 64 Audio IEMs

Price (Msrp): $1,100

Support our free service! Buying through our affiliate links costs you nothing extra:

Thieaudio Monarch Mk2 Scorings

Average Technical & Tuning Grades

Average Tunign Grade

A
  • Overall balance feels confident and refined, rewarding long listening sessions. A reliable all-rounder for everyday listening.

Average Technical Grade

A+
  • You get an articulate, polished performance with immersive stage depth and great control. There's a sense of polish across the whole spectrum.
Mids A+
You get reference-worthy mids that combine transparency, texture, and depth. It brings out emotional nuance beautifully.
Treble A+
Expect a radiant top end that paints every sparkle with precision. Harmonics soar without turning edgy.
Dynamics B
It handles shifts in volume well, keeping transients lively and controlled. Quiet-to-loud transitions feel natural.
Soundstage A+
Three-dimensional layering becomes effortless, placing performers on a lifelike virtual stage. Venue ambience wraps around convincingly.

64 Audio U4S Scorings

Average Technical & Tuning Grades

Average Tunign Grade

B+
  • It sounds pleasant overall, with some uneven spots that hint at room for refinement. Vocals remain pleasant despite the imperfections.

Average Technical Grade

B
  • An honest, middle-of-the-road performance preserves structure without chasing micro-detail. It's respectable for everyday listening sessions.
Mids A+
Midrange quality is superb, rich with resolving power and transparency. Micro-details leap out effortlessly.
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.

Thieaudio Monarch Mk2 User Reviews

Share your experience and build your personal ranking list.

You need to be signed in to write your own review
wpzdm
8.5

My vocal magic

Pros
Vocals that make you smile. THE most musical set for me.
Cons
Bass is okay for the price. Very occasional upper-mid sharpness

64 Audio U4S User Reviews

Example User Posted on ...
0.0

"This is an example review"

Pros
  • Example pro 1
  • Example pro 2
Cons
  • Example con 1
  • Example con 2
No User-Reviews Yet

Share your experience and build your personal ranking list.

You need to be signed in to write your own review

Find your next IEM:

IEM Finder Quiz

new
Use this quiz and answer a few questions to get your individual IEM recommendation list
(1/3) How much are you willing to spend on the IEM?
(2/3) Which sound characteristics are particularly important to you?
(3/3) Which tuning do you prefer?
You can select multiple options.
Buy

Footer