Testing Methodology: Measured using Arta via IEC 711 coupler to Startech external sound card. 7-9KHz peaks may be artefacts/emphasised due to my measurement setup which I found to be the case here. Measurements besides channel balance are volume matched at 1KHz. Fit depth normalised to my best abilities to reduce coupler resonance. Still, due to these factors, my measurements may not accurately reflect the earphone or measurements taken by others. I gave the S12 100hrs burn-in to ensure maximum performance prior to subjective breakdown.
Despite the vastly smaller chassis, it is actually the sound tuning that represents just how far miniaturized planar drivers have come. The S12 has been dubbed equally balanced and bright. As always, the reality lies in between. To me, this is a relatively balanced monitor that, at the time of this review, already has a proven track record of wide appeal. Relative to the popularized Harman curve, it provides a slightly wider bass-boost that extends further into the mid-bass giving it a lightly warmer and more forgiving presentation. The midrange sees a more aggressive rise but is balanced out in part by a hint of additional smoothness through the 4kHz range. The high-end sits just in front of the midrange giving the earphone an energetic voicing and a gentle U-shaped character just slightly biased towards the top-end. Due to dips between each of the three core frequency bands, it is a higher contrast sound that tends to prioritize separation over coherence and note body. Another notable quality is its impressive treble extension. This IEM has real sparkle and defined, fleshed out notes into the top-octave. Had you passed me this in-ear in a fancier shell at a fancier price, I may have been fooled. Alas, we should consider ourselves lucky that this kind of quality is now available at sensible prices.
If you’re familiar with the new Crop of Moondrop single-DD IEMs and the various other derivatives of the Harman curve out there, then you’ll be reasonably at home here too. The S12 has a few dB of enhancement over something like the KATO in the sub and deep-bass and this gives it a bold, powerful voicing. It isn’t pushed excessively into muddiness nor is the mid-bass overshadowed. In fact, I was impressed by the S12’s simultaneous punch in the mid-bass and authoritative slam in the sub-bass; this is certainly an IEM with plenty of energy in the bass despite not being an overtly bassy one. Those worried about excessive leanness should abate those fears.
Technically, this is an impressive performer too. I greatly enjoyed the Moondrop KATO and thought it a fine performer at its price tag. The S12 is clearly more defined and controlled through the bass range even with its increased note thickness. Notes have impressive definition and texture. Dynamics perform admirably, albeit I feel good dynamic driver in-ears like the KATO do enjoy a little more physicality yet in the sub-bass. However, above the S12 is noticeably more nuanced and controlled. Notes decay a little quicker and separation is improved as a result on complex tracks. They aren’t an especially bassy in-ear, but one with a good amount of fun factor and some of the best detail retrieval I’ve heard at this asking price.
I must concur with impressions already out there that the midrange is the weakest aspect of this in-ear, yet it remains an innocuous performer and will be a matter of taste. Usually, I am not opposed to 2kHz peaks, however, combined with a relative lack of upper-bass and lower-mid body, the S12 is left sounding a little dry and diminished. While vocals sit in good balance and midrange instruments just a step behind, the timbre isn’t quite as natural as you’d see on more progressively tuned earphones such as the aforementioned KATO. Chiefly, vocal size is reduced, they have a hint of strain to them that saps the liquid smoothness I enjoy from conventional Harman-inspired earphones. This rings most true for male vocals and is noticeable on female vocals to a lesser extent.
Fortunately, articulation isn’t over-sharpened, and sibilance wasn’t a notable issue in my testing either. The tonality is exceptionally clean too and note body is reduced but not pushed to coolness or metallic timbre. Layering performs well with strong contrast between foreground and background. Additionally, the revealing tuning brings small details further to the fore, compounding on the already more resolving driver to provide an impressively insightful listen. I wouldn’t expect high-end IEM quality here and, similarly, the S12 is outdone in terms of naturalness by some of its peers. Though not the highlight of this earphone, I didn’t find the midrange to stand as a glaring fault, though with limited appeal to those wanting perfect timbre.
This is where things get very interesting for the S12 has a tuning that is not uncommon in the high-end IEM space where treble tends to become brighter to bedazzle the listener. Some entry and even mid-level IEMs attempt to imitate yet without the resolving power to back it up. These fall to the wayside as brittle, strident affairs. The S12, however, does not suffer from the same fallibilities. It isn’t a bright, glaring monitor but simply a bright leaning one, and it has more then enough resolving power to ensure its proudly showcased notes are fully fleshed out. Indeed, emphasis starts in the lower treble and continues into the mid-treble too. Yet this isn’t a strident, over-sharpened in-ear but a crisp, cleanly presented one with just a hint of splashiness. I will also note that I confirmed measurements using a sine sweep as occasionally these peaks are due to coupler resonance rather than occurring on the IEM itself.
The leading edge is sharp, a little overly so but not stretched thin as notes maintain convincing body above. Cymbals decay natural and present a good amount of texture in turn. High hats are flattered by both excellent clarity and resolution that, for my ears, is unprecedented for a cheap IEM yet alone many costing a deal more. There’s a convincing sparkle and some real micro-detail retrieval here. To reiterate, don’t except 64 Audio Tia levels of extension and resolution, but surely something more suited to midrange asking prices rather than entry level. The note presentation indeed isn’t perfectly natural but on the vibrant side. They’re a little tizzy, a little over-sharpened, though to my ears still very much a pleasure to listen to.
With its strong treble extension, the S12 is capable of impressive expansion and, notably achieves well above average in-class width. Depth, meanwhile, is just about average in that it doesn’t hamper listening but doesn’t inspire either. Still, combined with a strong layering performance, this provides an immersive staging experience. Imaging is quite good but not class-leading as other aspects of this IEM have proven to be. It is a relatively intimate earphone that pushes foreground elements further forwards. This means its spaciousness is not often on full display. However, boot up a track with layers of backing vocals and you’ll find a wide, well-delineated image with a good sense of direction. Still, I cannot say it is the best performer in this regard. By contrast, separation is an impressive performer, benefitting from a high contrast tuning combined with a swift, defined note presentation. The ether between notes is palpable and this makes small details easier to isolate and appreciate.
With a 16 Ohm impedance and 102 dB sensitivity, the S12 is an efficient IEM and can achieve high listening volumes from portable sources. As we’ll see below, broad comments cannot be made about the quality of the sound from those sources as I’ve found this IEM to thrive with good amplification. Despite this, the S12 isn’t an earphone I’d consider difficult to drive, but does benefit greatly from a dedicated source of some kind. Consider this before purchase if that isn’t within budget for you.
Output Impedance Sensitivity
The S12 offers an almost flat impedance curve which means it should sound consistent from a variety of sources. There’s some bumpiness in the treble but in the magnitude of 1-2dB which wasn’t audible to me during testing. Of course, source colouration will still impact this earphone, but it does have a stable character between sources of differing output impedance. This is a plus for those wanting a consistent sound signature for professional work or simply those that want to use one set of IEMs with many different sources.
The S12 isn’t an inefficient earphone but still benefits notably from a dedicated amplifier/source. Switching between the Shanling M2X and my desktop stack revealed a noticeably more spacious stage and a more affirmative sub-bass impact on the stack. The S12 sounded thinner and less coherent from the portable source. In turn, I would advise investing in a powerful portable source should you want to listen to this IEM on the go, certain dongle DAC/AMPs such as the A&K Dual DAC and the S9 Pro were a noticeable step up. This is an IEM that scales sensationally with good amplification.
Suggested Pair Ups
As aforementioned, the S12 is best paired with a dedicated source, however, this can be as simple as a decent dongle DAC/AMP. Modern sources are getting very good so as long as you have something on hand, you will be extracting most of the potential from this IEM. As far as source colouration goes, I did personally enjoy this earphone from warmer sources. Despite bass being quite present already, I did find having a little more warmth and body in the midrange to enhance listenability. While it isn’t a sharp or brittle earphone, I would advise against already brighter sources due to its treble-happy nature which can offset balance. A neutral source can also be enjoyed for utmost tonal cleanliness.