By aspect — in detail
The strongest point of agreement, and the reason for its reputation: a neutral, reference-leaning balance with a modest sub-bass lift, widely called expertly tuned. The mild dissent is about character rather than correctness — a minority hear it as a little lean, forward or 'shouty,' and even fans concede it can read as 'too normal.'
“The MkII has an impeccably balanced profile”
Fc-Construct, Headphones.com
“I have several more expensive IEMs but the Monarch Mk2 is a better all-rounder than all of them.”
blorg, r/headphones
“I don't like the Monarch MK2 much because it has shouty upper mids and the weak bass quality to me.”
unfitstew, r/headphones
Measured
Crinacle characterizes the tuning as 'Neutral with bass boost' and grades tone S+ (his top tone grade), which is why it reads as reference-leaning rather than warm or bright. On an IEC-711 coupler its upper-midrange is notably forward, which is what a few listeners hear as 'shouty' at volume.
Quality is rarely questioned; quantity and slam are where it splits. Most hear the 10 mm DD low end as clean, textured and tastefully restrained — presence over bloat — and praise its control. A sizeable, measurement-literate camp finds it lacking in physical slam and impact for a kilobuck, with several calling weak bass the set's single biggest weakness.
Measured
Crinacle's 'Neutral with bass boost' tuning puts a modest sub-bass shelf over an otherwise reference balance, so the physical quantity is deliberately restrained — which is why the same low end reads as 'clean and controlled' to most and 'lacking slam' to others.
⚠ vs. listeners — How much weight you feel depends on the track, your tips and your source: the tuning is measured and restrained, so bass-quantity impressions vary more than bass-quality ones.
Where it splits
Clean, textured and tastefully tuned — quality over quantity, with real control rather than boom.40%
“There's a bass presence here that is excellently performed in its control and texture.”
Alex Schiffer, MajorHiFi
Underpowered for the price — mediocre slam and blunted impact, a possible 'Achilles heel.'60%
“I expect better for dynamic driver bass and there's a good argument for this being the Achilles Heel of the Monarch MKII.”
Precogvision, Headphones.com
Mostly a highlight, often called the set's calling card: natural, richly detailed vocals and instrumental timbre, part of why many prefer the MkII to the later MkIII. The caveat is a forward upper-midrange that can make belted female vocals sharp or fatiguing for the sensitive, especially at volume.
“the midrange of the Monarch MKII is beyond a doubt the IEM's calling card.”
Precogvision, Headphones.com
“many prefer the mk2 over the mk3 since the mk3 loses some of the midrange magic.”
JabbaWockey13, r/headphones
“I find myself wincing slightly and having to take breaks.”
Precogvision, Headphones.com
The set's most polarizing axis. Its Sonion electrostatic top end wins some of the highest praise in the class from one camp — extended, even, well-controlled and non-fatiguing — while a measurement-literate camp hears the same treble as artificial, 'metallic' and ultimately fatiguing, with 5 kHz presence that reads as sharp on percussion and weak air above 15 kHz.
Measured
On an IEC-711 coupler the treble carries strong presence around 5 kHz (measurements past the ~8 kHz coupler resonance aren't reliable). The updated Sonion ESTs add air but reviewers note limited amplitude above 15 kHz — which is why 'detailed but a touch artificial' and 'sublime' can both be defended from the same graph.
Where it splits
Some of the best treble in the class — extended, even, well-controlled and non-fatiguing.57%
“It's some of the best treble in an IEM I've heard in terms of the delicate balancing game of treble presence/brilliance, evenness, and timbre.”
Fc-Construct, Headphones.com
Artificial and fatiguing — a sharp 5 kHz presence and 'metallic' tinge that tire treble-sensitive ears.43%
“percussive hits have a certain sharpness to them that screams “wow, that’s detail!” on initial listen. But it’s ultimately fatiguing.”
Precogvision, Headphones.com
Soundstage
Moderate · 4 srcGenerally a strength, with one consistent shape: wide, well-organized horizontal width and easy layering, but limited height and depth. Nothing sounds cramped, but it isn't the most out-of-head, three-dimensional stage in the class.
“The MkII has great horizontal width and effortless imaging and layering.”
Fc-Construct, Headphones.com
“I get the feeling like the soundstage could be wider, but the stereo field only goes so far.”
Alex Schiffer, MajorHiFi
Rated a strength by most and a clear step up over the original Monarch — precise placement and clean separation, even if central images can be a touch soft. The dissent is a critical owner who found the imaging and separation only mediocre next to cheaper sets, a reminder that fit and source matter.
“Instrument localization is extremely defined in the side channels and while the Monarch MKII still lacks impactful center imaging, the layering issues the OG Monarch exhibited have been almost entirely mitigated.”
Precogvision, Headphones.com
“the separation and layering present a level of depth that’s instantly gratifying.”
Alex Schiffer, MajorHiFi
Genuinely disputed at the price. Its midrange resolution draws elite praise — matching two-kilobuck references in A/B for one reviewer — but its overall technical ceiling is contested: bass and treble detail are called more questionable, Crinacle grades technicals A+ rather than S, and a critical owner felt cheaper sets bested it.
Measured
Crinacle grades the MkII S+ for tone but A+ (not S) for technicals — very good, a notch below the outright technical leaders — which lines up with the 'elite midrange, merely-good extremes' split.
Where it splits
Reference-grade resolution, especially in the midrange — near the top of the class.60%
“The Monarch MKII legitimately has some of the best midrange detail I’ve heard bar none”
Precogvision, Headphones.com
Only good for the money — technicalities that cheaper sets can match or beat.40%
“The imaging, separation and detail were mediocre, easily bested by IEMs half the price that I've owned before, such as the Xenns Top Pro.”
FaustusRepent (owner), r/inearfidelity
Dynamics
Contested · 4 srcContested, and tied to the bass debate. One retailer review says ThieAudio fixed the original's flatness and was impressed by the contrast; the measurement-literate reviewers disagree, hearing muted macrodynamics and soft physical punch — the flip side of the restrained low end.
Where it splits
Improved over the original — good macro-contrast, no artificial loudness.15%
“was impressed by the amount of contrast the MKIIs were able to achieve.”
Jim Bates, Audio46
Still muted — soft macro-punch and physicality, the price of the lean low end.85%
“as a whole, dynamics perceptively come off more muted than I’d like on the Monarch MKII.”
Precogvision, Headphones.com
A real split, and worth checking before you buy. The shell is large and the metal nozzle thick (6 mm): some find it big-but-fine — even forgettable — especially after swapping to aftermarket tips, while others find it sticks out, presses, or won't sit securely for long sessions.
Where it splits
Big but livable — comfortable for hours, especially after tip-rolling to better ear tips.30%
“I don't think you will have fit issues with this IEM unless you have abnormally small ears. I often forgot that I was wearing it!”
Yagiz, Headfonia
Too large for some — a wide shell and thick 6 mm nozzle that stick out and can grow uncomfortable.70%
“I can fit them, but they stick out a tad and can get uncomfortable after a few hours.”
Precogvision, Headphones.com
A highlight at the shell: jewel-like custom resin with artisan 'molten-magma' faceplates and clean craftsmanship, plus metal nozzles that ease cleaning. The complaints are about the accessories, not the earpieces — the upgraded cable is heavier and uses protruding non-recessed pins, and the carrying case is plain.
“The IEMs look like gemstones and the craftsmanship seems quite good.”
Yagiz, Headfonia
“It's noticeably heavier than the old cable, though, so usability is not as good despite the better perceived quality.”
Precogvision, Headphones.com
“The carrying case is not a very fancy one, it looks and feels ordinary.”
Yagiz, Headfonia
Isolation
Thin evidence · 1 srcLightly covered by reviewers. The shell is vented for the dynamic driver, so passive isolation is ordinary by IEM standards rather than a strong point — fine for home and commute, less so for the noisiest environments.
“There is also a vent on the side of the shell, most likely for the 10mm dynamic driver inside.”
Yagiz, Headfonia
Split, and the used market only sharpens it. Fans rank it among the best price/performance in the kilobuck class and a legitimate endgame. Skeptics — including Crinacle's own low value rating — point out that it was a $300 price bump over the original, that far cheaper sets now get close, and that it's since been discontinued.
Measured
Crinacle grades the tuning S+ but the value only ★★ (2 of 5) — a signal that the sound is top-tier while the price-to-performance is unremarkable for the money.
Where it splits
A kilobuck standout — among the best price/performance in its class and a real endgame.55%
“Among the best price/performance ratios in this class”
Fc-Construct, Headphones.com
Hard to justify — a price hike over the original, and cheaper sets now get most of the way.45%
“the asking price for the new version isn't what I would say worth it coming from the cheaper Oracle MK2.”
Thumper_777, r/inearfidelity
