Thieaudio has consistently proven that it knows how to deliver standout IEMs; whether that’s the Oracle MKII, the Prestige LTD — which is still a great all-round musical option — or the flagship Valhalla, which is just on another level. But it’s the brand’s Monarch series that gets the most amount of attention, and deservedly so; I used the Monarch MKIII last year, and it didn’t take long to realize that these IEMs are truly special.
That’s why I was excited to get my hands on the Monarch MKIV; at the outset, the IEMs have a similar driver configuration that sees two dynamic driver, six Sonion balanced armature drivers, and two Sonion EST drivers in each shell, with a 4-way crossover and four sound tubes. Where things start to get interesting is the tuning switch, with Thieaudio adding a toggle on the IEMs that lets you easily switch between the reference neutral tuning and a much more engaging bass-focused sound. This Rumble mode (as it’s called), adds a 3dB boost to the entire sub-bass range, making the overall sound that much warmer.
Because of the tweaks to the sound tube and the custom tuning, the Monarch MKIV retail for $1,149 at Linsoul, and that’s for the standard model with the Stellashot or Kaleidoglow colors. If you want to go with a custom-shell design — as has been the case with previous Monarch IEMs — you’ll need to shell out an additional $100 to $150, and wait an additional six to eight weeks to get your order. I used the Monarch MKIV for the better part of three months now, and here’s why I think these IEMs are among the best in their category, and endgame-worthy if you’re looking to upgrade.
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The sound quality is sublime
With even $100 IEMs producing great sound, you’d want something that’s truly exceptional in a product that costs over a thousand dollars. Thankfully, Thieaudio knows what it’s doing in this category, and the choice of drivers along with the tuning makes the Monarch MKIV the best-sounding IEMs in the series yet. I tested the MKIV with my Fiio K19 DAC and M23 player, and I used the standard mode most of the time, switching over to the Rumble mode mostly while using the M23. With just 10Ω of power, you can use just about any source to drive these IEMs, and they’re not demanding in this regard.
Even in the default mode, the Monarch MKIV have a good sub-bass presence with a noticeable vibrancy, but it’s controlled well, and the mid-range has a clean presentation with vocals shining through and every small nuance easily noticeable. The treble is smooth and detailed, and it never gets harsh but still provides a sense of airiness. The standard mode is the way to go if you want a neutral sound with excellent technicality, but if you prefer a slightly warmer tonality, the Rumble mode is instantly accessible.
Custom tuning makes all the difference
As the name indicates, the Rumble mode boosts the sub-bass and mid-bass frequencies, and you get a definite rumble and energy that brings out the best in recordings.
If anything, the versatility that this unlocks makes the Monarch MKIV a much better choice than their predecessors. Just the ability to switch to a warmer sound with better musicality is great, and for me, this is a big differentiator.
That said, both modes have a thoroughly engaging soundstage that’s wide and detailed. The layering is exquisite, and this is immediately noticeable with ensemble pieces.
The design is better than previous generations
I’ve always enjoyed the design of Thieaudio IEMs, and the Monarch MKIV is no different. I got the Stellashot color variant, and it looks elegant while still making the IEMs stand out. Thieaudio switched out the usual resin designs and went with a metal chassis this time around, and the difference is immediately noticeable against the MKIII.
The Monarch MKIV have much better build quality as a result, and I like the heft that they provide; they’re not heavy or uncomfortable, but the shells are noticeably bigger than the MKIII variant. That said, the angled design of the sound nozzle means they’re still comfortable, and I didn’t have issues with the fit or any fatigue with extended use. The design goes a long way in this area, and even though the shells are quite big, the contoured fit provides a good isolation and doesn’t cause any undue pressure on the inner ear.
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Like previous models, the MKIV have a standard 2-pin connector, and the new tuning switch along the side lets you easily change the mode. The matte finish of the shell feels great to touch, and it prevents smudging and offers a decent amount of protection against scratches.
You get a decent set of accessories as well, along with a bundled suede case to take the IEMs anywhere. While I like the case itself, I would’ve preferred a slightly bigger option; as it stands, the case barely accommodates the IEMs, with no room to put a second set of ear tips. Outside of that minor issue, I don’t have any problems with the design or the accessories.
The cable also got an upgrade, with the eight-stand braided design ensuring you get a clean transmission without any interference. The modular cable has 3.5mm and 4.4mm plugs, allowing you to switch between the connectors as needed. The cable’s brown color stands out a little more than I’d like, and a standard black variant would have suited better in this context.
On the whole, I like the upgrades that Thieaudio introduced with the Monarch MKIV. The switch to a metal design makes these IEMs that much more durable, and while they’re bigger, they’re not cumbersome in the least. The tonality continues to be amazing, and the custom tuning with Rumble mode gives these IEMs a definite advantage. Coming in at $1,149, they’re a little costlier than the MKIII model, they’re easily among the best in this category.
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