Fit and Comfort

With larger IEMs such as the ThieAudio Monarch, you best hope you have good ear tops to take away some of the pain, especially if you have smaller ears. The absence of small-sized SpinFits is telling, and the larger-sized tips are puzzling. The Monarchs are the largest IEMs I have tested to date, so much so that they will jut out the ears and may fall off if not fit properly. This is why including the CP100, one of the best silicone tips, makes sense, as do the memory foam tips in different sizes. Once again, the artificial ear mold above about perfectly represents my own experiences, and the silicone tips work better in giving a nice, comfortable fit even over long periods of time. I still don't understand why there are no other provided options, and perhaps this is ThieAudio thinking that customers who are willing to shell out the cash for these will also be far more fussy and already have ear tips they prefer to use.

The foam tips are more finicky to get right, especially since these are made out of medium-density foam that squishes easily, and you will have to wait for them to re-form before trying again if not done properly. It might well be worth the effort to try these, but I already know that the SpinFit CP100 works really well for me, so I was quite happy using them. The Monarchs weren't too bad once angled in correctly, with three points of contact met at the antihelix, helicis crus, and antitragus while being inset in the concha. Smaller ears will definitely have issues, so maybe try something like the final Type-E tips that just rest at the entrance of the ear canal, but do note that this shifts the center of gravity further outwards, too. There are no complaints in terms of weight, however. Each ear bud weighs just over 7 g, and the cable provides further support as it goes over and around the ears. The vent on each bud also work nicely in providing a good balance of comfort and isolation.

Audio Performance

Audio Hardware

These are my first tribrid IEMs, so there is plenty going on here in that regard. We have looked at single-driver IEMs before, be it a full-range balanced armature (BA, not too common) or single full-range dynamic driver (DD, extremely common). Then there are the hybrid IEMs that use a combination of two different driver types, typically DD and BA, but sometimes DD and EST (electrostatic tweeter) drivers. Tribrids, as they are commonly known, use three driver types, and the common combination these days tends to be DD + BA + EST. With the Monarch, ThieAudio is using 1 DD + 6 BA + 2 EST drivers, with the dynamic driver being the same excellent 10 mm nano-membrane dynamic driver that worked so well in the Legacy 5. The bass section is taken care of by the dynamic driver and four of the Knowles balanced armature drivers as sub-woofers, also for a smooth transition to the mids, where the other two BA drivers work in conjunction with the two Sonion electrostatic tweeters on the treble range as best as possible since BA drivers alone can only do so much.

The drivers are complemented by the shell design itself, which has undergone more fine-tuning to make the angular structure better reflect sound waves, along with the abalone shell having been chosen with the harmonic signature in mind. With a rated total impedance of 26 Ω, driving these will take slightly more power than the average IEMs, but not to where a dedicated amplifier is needed. A portable DAC/amp or even dedicated DAP might be nice to have on the go, especially with the lack of a 3.5 mm jack on most phones today. If not on the go, space is less of an issue, but the 1.2 m long cable might be a potential handicap if connecting to a PC as the audio source. ThieAudio also rates the signal sensitivity at 112 dB and a frequency response of 20 Hz to 80 kHz courtesy the EST drivers, but good luck making use of that!

Frequency Measurement and Listening

I will mention that I have a general preference for a warm neutral signature emphasizing a slightly elevated bass and smooth treble range with detailed mids and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with an IEC711 audio coupler/artificial ear that ear buds can feed into to where there is decent isolation similar to real ears. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through the sound card. Size M silicone ear tips as provided with the IEMs are used unless specified otherwise. Testing begins with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally separately test the frequency response of each channel. Octave smoothing is at the 1/6th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the ear mold that fits to the audio coupler for a separate test to compare how the IEMs fare when installed in an ear geometry and not just the audio coupler by itself. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


Now, after calibrating the sound card and accounting for the base floor noise levels, I am a touch more confident about the SPL label, but there is likely still a significant offset across the board owing to the overall resistance and impedance in the system in addition to the operating volume/gain. The curves should also ideally be normalized to a set frequency, but the IEC711 is such that you can't really compare these results with most other test setups anyway, just within our own library of measurements. What is very useful information is how the left and right channels work across the rated frequency response in the ThieAudio Monarch earphones, or at least the useful part of it. The left earbud was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two are basically identical here. These are only available on a made-to-order basis irrespective of whether you are a single customer getting it directly from Linsoul or an authorized reseller. There is also a 2–4 week lead time, meaning ThieAudio has the luxury, and pressure, to get two perfect channels paired not only to each other but the chosen tuning for each of the nine drivers.


In fact, I am going to deviate slightly from my usual description here and praise the quality control and testing at ThieAudio even more. Here we see how the ThieAudio Monarch tests when fit into an artificial ear mold to better represent reality. This also involves the fit factor, so the audio coupler is typically a better idea for comparisons and a truer test of the factory tuning itself. With the artificial ear mold of the test setup, I used a different color to clarify it is still the right channel, though not directly fitted into the audio coupler (which remains there as a control). This is by far the closest I have seen both of these plots on IEMs, so much so that there is not even the characteristic peak shift in the highs I have noticed with single or hybrid driver IEMs. Perhaps it is the EST drivers catering to the highs in a way that has the signal this consistent, or the fit being quite good with the SpinFit CP100 in both. Perhaps it is the tuning with the much smoother treble response, or a combination of all three. I will also mention that a measurement was done right after unboxing and some general listening, before a break-in period of 50 hours to test for any break-in effect, of which there are none to be seen. When you are paying for such made-to-order products, you expect a higher degree of consistency and repeatability, and I am happy to report that the ThieAudio Monarchs made as a retail unit but then shipped for review set a new bar for me.

Speaking of setting a new bar, I delayed talking about the actual frequency response and my listening experience for another reason. I had actually lost my voice as a result of the ThieAudio Monarch. Well, not directly because of it—I had such a good time listening with these that I ended up in a solo karaoke situation in my apartment for over two hours and consequently lost my voice for the weekend thereafter. Remember when I said I prefer instruments over vocal? I liked the ThieAudio Monarchs so much that I actually listened to vocals for two hours as well. The rest of the weekend was spent listening more to classical music, smooth jazz, R&B, and pop.

Why not hip hop or metal? Well, these are not great for those genres. The ThieAudio Monarch is tuned with an emphasis on the mids. This means there is decent sub-bass, as seen above, but then we get a drop from 100 Hz and flattening out at 150 Hz, which is pretty unheard of. Those wanting a thumping bass will want to look elsewhere, especially with the non-existent mid-bass. There is a massive valley of the mids here, which makes for a reference-style tuning with precision held as a priority. The amount of detail you get in the mids is something you need to experience in person to appreciate, to where this is the first time I felt I could actually give up headphones for IEMs and not really lose out. There is enough range to distinguish all instruments, yet with enough of a change from the bass and treble range to where vocals are astonishingly clear too.

At the risk of coming off soppy, I may have shed a tear or two listening to some songs that evoked associated memories. One was also of the time I experienced professional tuning with the Sennheiser Orpheus at CES, and listening to Sarah Brightman and Andrea Bocelli saying it was time to say goodbye did it for me. As a control, I immediately swapped over to another IEM currently being tested (FiiO FH5s), as well as a set of planar magnetic headphones I am equally excited about (Audeze LCD-2 Classic). I got turned off the FiiOs, which isn't in the same ballpark, and the TheiAudio Monarch came quite close to the LCD-2 in the mids on the same setup. Pair the latter with a proper DAC/amp as befits those planar magnetic drivers and it scales beautifully, but this is what I meant about the ThieAudio Monarchs being the one for general use. This holds true with the soundstage as well, which is deeper and wider than any other IEMs I have had to date. Though proper headphones still can't be bested here, so there remains a use case for headphones nonetheless.

Funnily enough, the highs might be even better! I tend to go lighter on IEMs in the treble response because there is only so much you can fit in there and tune accordingly, but these tribrids go further by having the smoothest response tested to date. There are no ugly peak shifts as a result of no sharp peaks or dips across the board. The mids to treble response sets up the tone, and we end up with similar detail retained throughout without harmonic overlaps. Female vocals and tenors can be differentiated from string instruments, and it is only when you hear barely anything that you notice you are probably past the point of any reasonable music. Turn back to where Mozart on his piano reigns supreme on the Concerto No. 24, and the distinction between the treble and bass clefs will not go unnoticed, or underappreciated.

I went from having a less-than-impressive experience with the TinHiFi T5 to these, and what a change that was. Unfortunately, I currently do not have any other IEMs anywhere near the price range the ThieAudio Monarch operates in, so I can't do a direct comparisons except for the few done in various degrees thus far. Rest assured that it will show up if/when something comes up in the future, though. This is also why I am not talking too much about the balanced cable options here, as this is the first such implementation for me. All I can say is that it works, although the tuning is such that you don't really gain much going from stereo to balanced with these.