If you have been following the flagship In-Ear Monitor (IEM) space, you know the THIEAUDIO Monarch name carries serious weight. The Monarch MK2 set the benchmark for ultra-clean studio reference tuning, while the Monarch MK3 added sub-bass warmth and atmosphere.
Now, with the release of the THIEAUDIO Monarch MK4 (MKIV) priced at $1,149, THIEAUDIO introduces a hardware tuning switch and CNC-milled aluminum shells to bridge the gap between studio neutrality and full-bodied bass rumble.
Whether you are a music purist, a casual listener, or a competitive FPS gamer looking for pinpoint spatial accuracy, here is our full breakdown of how the Monarch MK4 performs.
Quick Verdict & Snapshot
- Driver Configuration: Tribrid — 2x 8mm Dynamic Drivers (IMPACT2) + 6x Sonion Balanced Armatures + 2x Sonion Electrostatic (EST) Drivers (4-Way Crossover).
- Price: $1,149 USD
- Build Material: T6 Aircraft-Grade CNC Aluminum Alloy (available in Stellashot or Kaleidoglow faceplate designs).
- The Highlight: A physical hardware tuning switch toggles between Standard Mode (clean reference) and Rumble Mode (+2–3 dB sub-bass lift).
- Best For: Competitive tactical shooters (Valorant, CS2, CoD) and music lovers seeking high resolution with customizable bass depth.
What’s in the Box & Key Upgrades
THIEAUDIO updated their build material, packaging, and accessory bundle significantly for the MK4 generation:
| Feature | Monarch MK4 |
| Driver Setup | 2 DD (8mm) + 6 BA + 2 EST |
| Shell Material | CNC T6 Aluminum Alloy |
| Price | $1,149 USD |
| Cable | 8-Braid Hybrid (SPC + OFC Copper) |
| Tuning Switch | Yes (Standard / Rumble) |
| Ear Tips Included | 3 Sets (Wide-bore, Narrow-bore, Foam) |
| Frequency Graph | Printed Card Included |
- Upgraded 8-Braid Hybrid Cable: A major step up from previous generations, utilizing an 8-braid blend of pure copper and silver-plated copper with modular terminations (3.5mm and 4.4mm balanced).
- Expanded Tip Selection: Includes three sets of ear tips—wide-bore silicone (blue stem), narrow-bore olive silicone, and high-density memory foam.
- Premium T6 Aluminum Shells: Moving away from resin, the CNC aluminum chassis offers a cool-to-the-touch, durable, and premium feel.
Design
The CNC-machined aluminum alloy shells feel exceptionally durable and lightweight in the hand. However, because it houses 10 active drivers per side, the shell footprint remains on the larger side. Users with smaller ears may feel outer-ear fatigue during long 4- to 5-hour gaming or listening sessions.
The standout feature of the shell is the On-Board Tuning Switch:
- Standard Mode (Red Indicator Off): Delivers a flat, reference-grade sub-bass shelf, maintaining pristine mid-range clarity and ultra-fast transient response.
- Rumble Mode (Red Indicator On): Engages a +2-3 dB lift across the sub-bass and lower-mids below 1,000 Hz, adding immediate weight, warmth, and impact without introducing mid-bass mud.
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Sound Quality
1. Low End (Bass)
In Standard Mode, the bass is tight, fast, and surgical. It decays quickly, keeping the mid-range spotless, ideal for critical listening and audio mixing. Flip the switch to Rumble Mode, and the dual 8mm isobaric dynamic drivers unleash a deep, authoritative sub-bass punch. Tracks from Kendrick Lamar or R&B playlists transform into an immersive live concert experience without bleeding into the vocals.
2. Mid-Range (Vocals & Instruments)
Vocals are forward, crisp, and intimate. Male vocals gain a touch of density in Rumble Mode, while female vocals and acoustic instruments remain airy and transparent. The crossover integration between the dynamic drivers and Sonion BAs ensures smooth transitions across the frequency spectrum.
3. Highs (Treble & Technicalities)
Thanks to the updated Sonion EST driver crossover implementation, upper-treble extension is vast and airy. Details like high-hat shimmers, string frictions, and subtle room reverberations come through with incredible clarity. The 8 kHz to 13 kHz air region is subtly elevated over the MK3, yielding a wider, more open soundstage.
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Gaming Performance: An FPS Powerhouse
In competitive gaming tests across Valorant, Call of Duty, Apex Legends, and CS2, the Monarch MK4 comfortably earns an S-Tier placement:
- Precise Spatial Imaging & Depth: The depth perception is razor-sharp. In Valorant, hearing a single footstep behind a wall lets you pinpoint enemy movement instantly.
- Clean Layering in Chaotic Fights: Even when airstrikes, grenades, and heavy gunfire erupt in Call of Duty, individual sound cues remain separated.
- Switch Versatility for Games:
- Standard Mode: Best for Apex Legends and CS2, keeping gunshot pop restrained while maximizing distant footsteps and climb sounds.
- Rumble Mode: Highly effective in Valorant and CoD, adding a satisfying thud to gun reloads and wall-banging footsteps without sacrificing spatial awareness.
Tip: Pair the Monarch MK4 with the included memory foam ear tips for gaming. The foam slightly dampens sharp high-frequency gunshot noise while enhancing noise isolation and comfort during long sessions.
Final Thoughts
The THIEAUDIO Monarch MK4 is one of the most complete flagship IEMs on the market today. By giving listeners instant hardware control over the low-end frequency response, it eliminates the compromise between studio neutrality and head-bobbing musical engagement.
If you are looking for an endgame set that excels equally at music reproduction and competitive FPS gaming, the Monarch MK4 is worth every penny of its $1,149 price tag.
FAQs
You want clean, highly resolving “flagship” sound: You crave ultra-clear resolution where micro-details, vocal textures, and crisp highs come through with zero blur or grain.
You want a warm, relaxed “laid-back” sound: The MK4 is energetic, revealing, and forward; if you prefer a dark, soft, or forgiving signature for poorly recorded tracks, this set might feel too intense.
It is a hyper-resolving, clean-neutral tribrid IEM with a massive, atmospheric soundstage, paired with a hardware switch that transforms it into a warm, hard-hitting bass monster on demand.
In Standard Mode, it delivers a surgical, reference-style tuning with a flat sub-bass cutoff and clean lower-mids. Flipping the switch to Rumble Mode adds a +2–3 dB low-end lift, giving kick drums and electronic basslines a thick, physical slam without muddying vocals.
Because it houses 10 drivers per side inside a CNC aluminum shell, the footprint is on the larger side. While the ergonomic shape rests smoothly in most ears, listeners with smaller ear canals may experience fatigue during extended 4+ hour gaming or listening sessions.
It is an absolute S-Tier pick for FPS games like Valorant, CS2, and Call of Duty. The depth perception and spatial imaging are pin-point precise, making it effortless to track enemy footsteps through walls and hear footstep cues even during heavy gunfire.
