{"id":2402,"date":"2026-05-12T10:51:03","date_gmt":"2026-05-12T02:51:03","guid":{"rendered":"https:\/\/www.gothamproaudio.com\/others\/mystori-m-121i-mystery-princess-hybrid-unit-in-ear-headphones-experience-tds-review\/"},"modified":"2026-05-12T10:55:01","modified_gmt":"2026-05-12T02:55:01","slug":"mystori-m-121i-mystery-princess-hybrid-unit-in-ear-headphones-experience-tds-review","status":"publish","type":"post","link":"https:\/\/www.gothamproaudio.com\/en\/media-coverage\/mystori-m-121i-mystery-princess-hybrid-unit-in-ear-headphones-experience-tds-review\/","title":{"rendered":"Mystori M-121i ‘Mystery Princess’ Hybrid Unit In-Ear Headphones Experience – TDS REVIEW"},"content":{"rendered":"\n
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TDS REVIEW and TDS Quick Talk are both based on the TDS Studio scoring standards and content description V202402.<\/em><\/p>\n\n

KT MARK for the models involved under the market background at that time:<\/strong><\/p>\n\n

Mystori Audio M-121i: IV (Recommend)<\/strong><\/p>\n\n

\u00b7Design, Fit & Acoustic Structure<\/strong><\/h5>\n\n

The M-121i comes in only one color scheme, with the shell featuring a deep purple hue that leans slightly reddish. The shell is made of resin and 3D printed, offering a good level of transparency. The gap between the faceplate and the shell is very narrow and even, showing a high level of craftsmanship. There is a metal frame around the faceplate with an anodized finish, while the faceplate itself features hand-painted patterns. The M-121i faceplate blends various colors, primarily purple and black, with some added glitter, giving it a distinct look. Since they are hand-painted, every single unit has a slightly different appearance.<\/p>\n\n

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The shell shape is basically like a standard semi-custom mold, but slightly elongated. This means there’s a chance it might press against the upper edge of the concha, but as long as you don’t have particularly small ears, there shouldn’t be any major fit issues.<\/p>\n\n

The inner structure of the shell has been adjusted for the ear’s anatomy, with a high level of fullness in the cavum and cymba areas. The fit is quite good. The shell is somewhat thick, so wearing them while lying on your side isn’t recommended.<\/p>\n\n

A metal mesh is visible at the nozzle. According to Mystori Audio, the low-frequency damping inside the shell has also been specifically tuned. The nozzle thickness is moderate, offering good compatibility with various ear tips. There are two main vents on the shell surface, located at the top and below the socket, while the inner side has no openings. The three vents at the top allow more air for the dynamic driver. The passive isolation is pretty good for this type of semi-custom shell, and there are no obvious pressure balance issues.<\/p>\n\n

\u00b7Cable, Driver & Power Demand<\/strong><\/h5>\n\n
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By default, Mystori Audio pairs the M-121i with a shielded cable labeled as 6N single-crystal copper. It’s a four-strand braid with decent tightness. Since the individual strands are thin, the overall cable isn’t bulky. The surface is covered in a nylon mesh for shielding and protection; it’s soft and doesn’t tangle easily. Currently, only a 4.4mm balanced plug option is available.<\/p>\n\n

The detachable cable system uses a 0.78mm 2-pin flush socket. The socket isn’t recessed, so it’s compatible with most flush or protruding pins. The pins on the cable side fit very tightly. The cable pins protrude by about 2mm and feature a keyed design, making them usable with most flush or recessed socket earphones.<\/p>\n\n

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Regarding the driver configuration, the M-121i features a hybrid four-driver architecture per side: one dynamic, two balanced armatures, and one planar driver. A titanium-plated PET composite diaphragm of unknown diameter handles the lows, a set of composite BA drivers handles the mids, and a micro-planar driver handles the highs in a typical three-way crossover setup. You can clearly see the three-tube structure through the shell. It’s worth mentioning that due to the characteristics of the titanium-plated diaphragm and the micro-planar driver, this is one of the few IEMs I’d recommend actually burning in for a while before listening. You don’t have to go out of your way, though; it reaches its peak state relatively quickly.<\/p>\n\n

Impedance is 32\u03a9 with a sensitivity of 107dB\/mW. On paper, the M-121i seems like it might need a bit of juice but doesn’t require massive power to reach a decent volume. However, to really drive it well, you actually need a fair amount of power reserve. Personally, I’d suggest starting with something like the CDA-M2 as a minimum. Style-wise, it doesn’t pair great with cold or neutral sources. You’ll get a better listening experience by pairing it with a source that sounds fuller or even slightly warm. The less-than-stellar impressions from trade shows were likely due to the stock ear tips and source pairings, as well as the fact that the demo units were brand new and completely un-burned-in, according to the manufacturer.<\/p>\n\n

\u00b7The following sound description is based on the original cable with balanced drive and the manufacturer-recommended Pentaconn COREIR brass core ear tips, with sufficient power provided.<\/p>\n\n

\u00b7Sound Description<\/strong><\/h5>\n\n
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The low-frequency quantity is moderate to slightly lean, with thickness and fullness being quite restrained. The elasticity is good, and the sub-bass extension is appropriate for the price point. The decay is relatively fast with little lingering resonance, making it sound very clean. The atmosphere and richness are quite light. The M-121i’s bass sounds fast and clean; you get a similar vibe even on low-power devices, but the elasticity and layering improve significantly with the right pairing. Instruments with fundamentals in the lower-mid range don’t suffer from obvious forwardness.<\/p>\n\n

In the midrange, the vocals aren’t too close\u2014they don’t feel “in your face,” but they don’t get lost behind the instruments either. Because of the physical crossover of three different driver types, the imaging solidity can’t quite compete with a single-driver setup. Instead, the M-121i emphasizes a sense of vocal delicacy with a slightly larger mouth shape. It leans more toward defining lines and textures rather than raw body, though it’s more balanced with the original ear tips. The COREIR tips tend to sharpen those lines. Regardless of the tips, the vocal texture isn’t thick. From this perspective, it’s easy to see why many people enjoy its performance with female vocals. In reality, it doesn’t lean heavily toward male or female voices; it just suits vocal ranges that aren’t overly heavy. With coarser or thicker vocals, this setup can feel a bit thin in the lower registers and generally stiff. Smoothness is good, and graininess is minimal. There isn’t much coloration in the vocal range; the tuning is mainly for delicacy. This, combined with the texture adjustments, keeps the M-121i from sounding completely flat. Throat sounds are slightly higher than standard, the breathiness is moderate but slightly emphasized, and sibilance has been smoothed over. Transparency is good.<\/p>\n\n

For instruments, there’s a similar emphasis on lines. Among string instruments, violins, violas, and guitars have a very catchy tone with prominent delicacy and emphasized plucking details. The cello feels lean but takes up a fair amount of space. Brass instruments have controlled momentum, while instruments needing brightness, like trumpets, have plenty of it. Woodwinds sound reasonably natural with a slightly enhanced sense of air. Instrumental harmonics initially feel like they’re trying to be emphasized but aren’t quite fluid; this improves as the drivers settle in. In percussion, the kick drum has moderate presence, the snare snaps very quickly, and cymbals are quite bright\u2014thankfully not to the point of being piercing or overly metallic.<\/p>\n\n

The high-frequency brightness is moderate to slightly bright, with plenty of energy in the upper-mid transition and some noticeable peaks. The COREIR tips further enhance this. The ultra-high frequency extension is appropriate for the price, with a roll-off that starts a bit early but isn’t too abrupt.<\/p>\n\n

\u00b7Summary & Recommendation<\/strong><\/h5>\n\n
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With the officially recommended COREIR tips, the M-121i is a very specialized-sounding IEM. It’s great for thinner vocal performances and suits listeners who enjoy a delicate instrumental style. It handles most pop music in that vein well, but for blues, rock, or electronic music where bassline energy is key, I’d suggest trying tips with a smaller opening. It’s not really suited for metal. When listening to anisong with poor recording\/mixing or complex arrangements, the upper mids can sound a bit chaotic, while the default silicone tips might make the details feel less prominent. For acoustic genres, jazz isn’t really its forte, but for small to medium instrumental ensembles where imaging precision and low-end thickness aren’t critical, it performs well for the price. Again, it’s very hard for non-coaxial hybrid IEMs to form a perfectly stable image.<\/p>\n\n

Overall, as Mystori Audio’s first IEM, the M-121i shows the new brand’s clear ideas on design and tuning. Its technical performance has a slight edge at this price point, though it is quite picky about pairings, which is rare in today’s market. Among hybrid IEMs in the $150-$200 range, its ability to make instruments and female vocals sound catchy provides a noticeable upgrade for many entry-level listeners.<\/p>\n\n

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Source: TDS Audio Experience<\/p>\n<\/blockquote>\n\n

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View Original Article<\/a><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

TDS REVIEW and TDS Quick Talk are both based on the TDS Studio scoring standards and content description V202402. KT MARK for the models involved under the market background at that time: Mystori Audio M-121i: IV (Recommend) \u00b7Design, Fit & Acoustic Structure The M-121i comes in only one color scheme, with the shell featuring a […]<\/p>\n","protected":false},"author":9,"featured_media":2399,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[31],"tags":[46],"class_list":["post-2402","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-media-coverage","tag-mystori-audio-m-121i"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/posts\/2402","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/comments?post=2402"}],"version-history":[{"count":1,"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/posts\/2402\/revisions"}],"predecessor-version":[{"id":2410,"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/posts\/2402\/revisions\/2410"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/media\/2399"}],"wp:attachment":[{"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/media?parent=2402"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/categories?post=2402"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gothamproaudio.com\/en\/wp-json\/wp\/v2\/tags?post=2402"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}