Thieaudio Monarch MK3 VS Symphonium Audio Helios SE

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Thieaudio Monarch MK3 takes the flagship slot with swagger: a 2DD + 6BA + 2EST array and a 4-way passive crossover, centered on the Impact² isobaric push-pull dual 10 mm subwoofer. The shells are huge and gorgeous (plain backs at ~$1000, fancy backs around ~$1100), vented on the underside, and paired with a supple, interchangeable-plug cable (2.5 / 3.5 / 4.4). Despite the driver count, coherence is the headline: this isn’t a parts parade—it’s a single, surgically precise instrument.

Sonically, bass behaves like a well-tuned subwoofer in a treated room: tight, fast, and slammy without bloat. The real party trick is imaging and spatial “distance”—sounds lock into place with eerie specificity, making familiar tracks feel new. Instrument separation is crystalline, treble air is effortless, and the set is easy to drive yet scales—more power refines rather than merely getting louder. Tip rolling matters: stock foams/silicones are okay, Dekoni helps, Dunu S&S can fit oddly on these large shells, while Render tips seal the room and boost performance ~15–20%, supercharging the imaging and engagement.

Against the Monarch MKII (good, kept around), the MK3 feels like a different tier—the sort of tuning that glues ears to music and makes skipping tracks impossible. Accessories are minimal because the message is clear: you’re buying the sound, and it arguably feels underpriced for this level. Currently on pre-order, this is peak IEM energy—an endgame-grade, king-making performance that invites hyperbole and earns it.

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Limited to 50 units and co-signed with Elise Audio, Helios SE shows up as a 4BA oddball with a vibe: ultra-relaxed, non-aggressive, almost like every track sits one gain click lower than expected. Vocals sit nicely centered, instruments hang back, and stage/separation can flip between muted and “whoa” micro-split moments. Tip rolling swings the personality hard—silicons keep it chill, foam-style tips shove vocals forward and magnify the weirdness; think “interesting” more than “reference.” It’s an experience-first tuning that doesn’t try to punch for attention and can feel almost too polite on energetic songs.

Build is simple, soft cable, occasional twist mismatch, and some units in 3.5 mm that don’t scream “kilobuck.” The pitch here is rarity and flavor: graph glued to the box means nothing about how it actually feels—this is human-ear stuff, not squiggle worship. As a collection piece for lovers of unusual BA staging and “just chill” listening, it charms; as a $1k+ value play, not so much. The verdict: likeable around $500–$600 on novelty and tuning alone, but at four-figure pricing it’s more “own something rare and weird” than a slam-dunk daily driver.

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Bass is where the Monarch MK3 steals the show: tight, textured, and rumbly with real slam and no bleed, giving male vocals a more natural heft while staying clean. The Prestige LTD pushes the low end back for a lighter hit but trades that for a more open, airy stage and superior layering—great for busy mixes like rock, metal, and classical. The Hype 2 mirrors the LTD’s bass balance and rumble conceptually, but lacks the same overall technical resolve, making the MK3 the better pick for pop, EDM, R&B, and hip-hop that benefit from weighty sub-bass.

Through the midrange, the LTD steps ahead on separation, detail, and note definition, presenting vocals slightly set back yet more airy and sparkly; female vocals especially shine. The MK3 counters with more weight and engagement on male vocals and a forward presence, though its stage isn’t as deep or spacious as the LTD (a modest vertical lift over Hype 2, but not a “$1k soundstage”). Up top, the LTD has the smoothest, best-extended treble with the most air and microdetail of the trio. All three excel at moderate volume, but none invites cranking like certain high-volume specialists.

As an all-rounder, the MK3 checks nearly every box yet misses that distinctive “special sauce” expected at its price; think ~15–20% uplift over Hype 2. The LTD delivers the bigger technical jump at roughly 25–30%, with staging, extension, and air taking the crown, making a strong case paired with a cheaper daily driver. The Monarch MK2 still earns a nod for its midrange/vocal magic if that’s the priority. Final word: both LTD and MK3 score an S; for those willing to spend, they’re easy to recommend—just match the tuning to the library and the qualities valued most.

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Thieaudio Monarch MK3 steps up as a true flagship: a 2DD + 6BA + 2EST hybrid with high-grade Knowles/Sonion drivers, a gorgeous marbled faceplate, and—crucially—a vastly improved shell over MK2. Comfort moves from a 2-hour limit to all-session wear, and the stock package (solid cable with swappable terminations, foam and silicone tips) is well thought out. Tip choice meaningfully shapes performance; options like SednaEarfit Short or Comply foam push it toward its best.

Tuning follows a balanced, studio-leaning tonality with extra sub-bass warmth, delivering both clinical insight and genuine fun. Micro-detail is standout, bass is clean, textured, and physical (from Nirvana’s “Lithium” to modern hip-hop drops), and male vocals are among the most convincing heard on an IEM in this tier. Stage is wider and a bit taller than MK2, with excellent imaging, layering, and separation, keeping drums, bass guitar, and synth lines neatly organized without blunting impact.

For competitive gaming, the MK3 brings a tight soundstage, strong depth perception, and clear audio cue emphasis, offering precise 360° placement and adequate verticality. Versus Prestige Limited, it trades some sterile clinical edge for a more engaging, atmospheric presentation that reads distance and urgency better; compared to Yanyin Moonlight Ultra, it’s the more coherent pick for both games and music. While great mid-fi options like Zens Top, Orchestra Lite, or Yanyin Canon 2 remain strong, Monarch MK3 feels like the elevated, “dreamy” flagship experience—a new top choice for music enjoyment that also dominates in game when properly tipped.

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Symphonium Audio’s collaboration with Elise Audio turns the original Helios into a more wearable Helios SE without rewriting its sonics. The shell is smaller, cleaner-looking, and finished in teal, moving from “bulky and awkward” to a still medium-large but more secure fit. It remains unvented, so insertion technique matters, and fit security is improved rather than perfect. Accessories include a metal puck case, cleaning tool, and even a per-unit frequency response slip; the thin stock cable behaves well (4.4 mm on the loaner, 2-pin without earhooks). Power needs are modestly higher than average for an IEM but nowhere near full-size headphones. Only 50 units are being made at roughly $1,200.

The tuning mirrors the OG: a lean, bright-neutral balance with a midrange-forward center, very extended treble, and a sub-bass boost atop lean mid-bass/lower mids. Vocals pop with clarity and texture, and the treble is unusually incisive yet smooth, contributing to a stage that’s wide for the price. Despite using only four balanced armatures, sub-bass notes hit with convincing physicality—surprisingly close to a DD—when the track has true low-end content. The flip side: kick-drum-centric or classic-rock mixes can feel dry, the stage depth varies with bass content, and ride cymbals trade some metallic “ping” for a slightly swishy decay.

Versus peers, 64 Audio’s U4s reads as bassy-neutral with thicker mids and the most inherently tactile bass (it’s a DD, after all), while 7th Acoustics’ Supernova sits closer to neutral with fuller lower mids, sharper imaging, and a vented shell that locks in securely. Helios SE’s value is crystal-clear: keep the Helios’ stellar treble performance and wide headstage, fix the ergonomics, and leave the core tonality intact. It’s a set to respect more than love for those craving warmth, but for enthusiasts chasing clean, airy resolution and vocal focus, it’s a confident 4/5.