Next in line is Perfect Seal’s Deca, a 10 BA ciem that evolved from its smaller sibling, the AR6. With a tuning that resembles Lime Ears’ Aether, Deca shares some defining traits – specifically, a gorgeous upper midrange and natural tonality.

Perfect Seal Deca
-Drivers:                    10 BA drivers
-Design:                     5-way crossover, 3 sound bores
-Impedance:             48 Ohm
-Sensitivity:               116 dB
-Fit:                             Custom

-PRICE:                        $1450


The industry standard Plastics One 3-wire OFC cable has a warm tonality, which primarily results from its rolled off upper treble, and lightly enhanced upper-bass. The midrange is linear, resulting in an overall neutral note size. While the mid-bass is warm and natural in tone, it’s not particularly controlled. Accordingly, the loose bass results in a warmer stage structure. This affects the airiness of the stage as well as its transparency; especially since its top end does not extend very far. However, while the cable doesn’t perform very well when it comes to resolution and transparency, its warmer tone results in a fairly smooth and natural signature.

Similar to the previous reviews, the pairing isn’t particularly good or bad. Its warm tonality adds a smooth touch to Deca’s clear upper midrange so the pairing works fine, even though it doesn’t improve its performance.

Sound impressions

Following Perfect Seal’s house sound, Deca is tuned with a lightly warm tonality and natural sound – the general focus of its tuning is on tone. Its recipe: enhancing the upper midrange, while attenuating the lower treble. The result is a beautiful midrange, with a soft and smooth treble. If this sounds familiar, it’s because Deca follows a very similar curve to the previous-in-line; the Lime Ears Aether. But Deca trades a bit of midrange body for a crisper sound, and greater transparency.

Deca’s clarity results from boosting the 5 KHz range. It’s a difficult range to tinker with, for its pronounced effect on the presentation. There are benefits to reap. The most pronounced being a more natural shade of clarity compared to boosting the treble, which can easily sound bright or artificial. But it’s also a sensitive area. It easily tends to harshness, while it has an inverse relationship with the lower midrange. The trick is to balance its tone with the right amount of bass and treble, something Aether has previously demonstrated of being capable to doing right.

Deca’s bass is neutral-to-light in overall quantity. Accordingly, it doesn’t create particularly thick notes. Instead, the presentation comes across as light-footed and airy. The stage has a spacious feel due to the neutral bass, with just the slightest breeze of warmth passing through. Much like Aether, Deca creates a classic stage with greater width than depth and height, in good proportions. The stage positioning is fairly neutral, with notes as well as vocals being neither particularly forward nor laidback. It’s a relaxed presentation, that isn’t too upfront. However, while Deca’s stage is more than adequate in its overall proportions, its layering behind the vocal can be a bit tight, while it misses a bit of pinpoint accuracy in its imaging. Nevertheless, its separation is more than adequate based on the size and airiness of the stage.

As mentioned, its bass can be considered neutral – but it’s lighter than average. Most manufacturers choose a slight emphasis on the low end to add a bit of energy and rhythmicity. It’s an unobtrusive bass, performing steadily in the background. It isn’t necessarily the most engaging bass, but it’s relatively fast and airy. In addition, its hits are tight and well controlled – there isn’t much weight to carry around.

Rather, it’s an audiophile tuning of the bass, focusing on tone and quality, rather than sheer impact. Its low-end extension is good, as is its definition. But there are also important advantages resulting from Deca’s attenuated bass: specifically, the airiness of the stage and the midrange transparency.

Deca’s midrange is primarily characterized by an upper midrange peak, providing a clear and open sound. There’s a certain lightness to it as it’s only slightly warm, but natural in tone. The upper bass and lower midrange however are laidback in the presentation, resulting in a leaner structure of midrange notes. Cellos or heavier electric guitars for instance might miss a bit of weight, that extra bit of power to make them sound more impressive.

But what the lower midrange might lack in body, it more than makes up for in the upper midrange’s tone. For this truly is one of the finest upper midranges money can buy. It’s both remarkably clear, as well as accurate in timbre. Aether’s upper midrange is a bit warmer, but Deca’s is simply purer; whether the pluck of an acoustic guitar, or stroke of a violin – they resonate with a magnificent beauty. It’s a very transparent sound, succeeding in its ability to sound clear without sounding bright.

This returns in the vocal presentation. The forwardness of the vocals tends to fluctuate a bit, shifting between neutral to slightly forward depending on the track. But especially deeper male vocals miss a bit of body – it’s not a very dense or powerful vocal presentation. Their tone however is good, with just the right amount of warmth for them to sound realistic. Female vocals on the other hand truly flourish – there’s a certain sweetness to their song, balancing clarity with tone and enough solidity.

Deca’s signature is finished off with an attenuated treble, resulting in an overall natural timbre. This is a very smooth, yet sufficiently clear and detailed treble. In addition, Deca retains a safe margin when it comes to sibilance. It isn’t an overly sparkly monitor – the treble won’t jump out to catch your attention. And as Deca’s resolution is about average and its lower treble is attenuated, it isn’t particularly upfront in its detail retrieval. Especially finer treble details relying on the higher frequencies can be more of a musical side note; but they’re nevertheless part of the flow, just less prominent – there’s sufficient clarity on the stage for all the detail to emerge.

Within its tuning, dipping the lower treble is a necessity for the overall naturalness of the presentation. Accordingly, it gives notes a softer attack, and the general focus shifts away from analytical precision. The downside is that its imaging misses a bit of the pinpoint precision you’ll find with monitors like the EarSonics S-EM9 or NT6pro. Clearly, there’s a tradeoff off of smooth musical flow and naturalness, for that final bit of accuracy. In addition, its treble extension is only around the iem average of 10-11 KHz, as is its speed. However, as both its definition and tone are quite good, it’s overall an enjoyable treble to listen to.


Lime Ears Aether (€1150)
Deca and Aether share more similarities than differences when it comes to tone and performance. As a result of their tuning they both sound very natural, although there are various differences here and there. For starters, Aether is tuned with slightly more mid- and upper bass emphasis. As a result, it’s tone is balanced with a bit more lower treble presence. As Deca’s mid-bass is laidback, its lower treble is dipped a bit further. The slight variations affect the presentation in several ways.

For instance, while their stage is similar in proportions, Deca’s attenuated mid-bass opens up its stage, resulting in a more airy and spacious feel. In addition, its midrange gains in transparency. However, Aether betters Deca in its layering ability, while its imaging is more precise. Overall, this results in a more focused image. But as Deca’s stage feels slightly more spacious and airy, their general performance in separation is still quite similar, with neither having a clear advantage.

Aether’s bass has more low-end impact, and increasingly so with its bass switch on ‘up’. Accordingly, its bass provides a warmer tone to the midrange, as well as warmer air on the stage. Deca’s bass has less quantity, but improves in low-end extension as well as definition. In addition, its bass is a bit faster. Due to its greater quantity, Aether’s bass can be considered more engaging. While Deca’s bass retains a somewhat distant position in the background, its quality is slightly greater.

But Aether’s midrange benefits from its greater upper bass emphasis; it creates a thicker note structure, with more body on midrange notes, as well as a warmer tone. Compared to Deca’s laidback lower midrange, Aether’s is more neutral. The vocal presentation is thicker as well as denser, although their position on the stage is similar in terms of forwardness. Deca’s upper midrange however is crisper and purer, while Aether’s is warmer. However, overall their midrange can be considered variations of a similar tuning.

Aether’s lower treble has a bit more presence compared to Deca. This gives it a bit more sparkle, as well as precision. Deca’s lower treble dips a bit further, so it trades a bit of detail for a smoother presentation. In addition, Aether’s treble is a bit faster, although the differences are not great. Similarly, their extension is roughly the same, as is their resolution.

Hidition NT6pro ($1200)
The NT6pro is one of the technical high performers, focusing on precision over naturalness – a contrast to Deca. With greater resolution and more accurate imaging, the NT6pro’s presentation is more precise, while being more upfront in its detail retrieval. Deca on the other hand is not only smoother, but more accurate in tone. Especially when it comes to the upper midrange, it’s a case of beauty versus precision – but that doesn’t mean the NT6pro can’t equally shine.

Both monitors create a fairly classic stage in dimensions, although the NT6pro’s is slightly flatter and less wide. What it loses in size, it gains in airiness: this is a spotlessly clean stage. As both its layering as well as imaging is more precise, the NT6pro more successfully creates a holographic image. While Deca’s separation doesn’t necessarily leave one wanting, the clarity and precision of the NT6pro is nevertheless a significant improvement.

The NT6pro’s bass has similar extension, but greater definition due to its enhanced treble. Its bass is more resolved, although Deca’s is more natural in tone. As the NT6pro’s bass is lightly enhanced, it betters Deca’s more neutral bass in impact. In both cases the speed is good. Overall, the NT6pro’s bass is slightly more technical and engaging, while Deca’s is more natural in tone.

Deca’s midrange is roughly similar in warmth as the NT6pro. The NT6pro might have a brighter treble, but a bump in its midrange results in a nice bit of forwardness in the midrange. Accordingly, its vocal presentation is slightly denser. Its vocals have a bit more body, but its instruments are leaner – the result of an upper midrange dip. Deca’s instruments not only better the NT6pro in size, their timbre is more accurate; the NT6pro’s are brighter by comparison.

The NT6pro’s treble is one of its defining feats; while enhanced, it remains relatively smooth. And it sparkles, to say the least. Not something Deca can quite keep up with, although this must align with one’s preference. But to be fair, there isn’t much that sparkles like an NT6pro. As a result of its greater treble quantity, it’s more upfront in its detail retrieval. Deca’s treble is certainly smoother, but not as precise. In addition, the NT6pro’s treble has the better extension, and slightly better speed. But importantly, Deca has the more accurate tone.

The verdict

Every manufacturer puts their heart and soul in their creation, and comes up with something they feel is ‘right’. Just like with listening preferences, when it comes to tuning there isn’t a case of wrong or right. Each has their own philosophy, their purpose. This was the case with the 8.2 and Aether, and it’s certainly clear to see what Mike was going for with Deca.

Deca’s midrange can truly shine. Key to its signature is its upper midrange peak and beautifully attenuated treble. This not only results in a smoother treble, but an overall accurate timbre – Deca is one of the more natural sounding monitors. Its tone is above average for string instruments like acoustic guitars, although they lose a bit of engagement once they’re plugged in.

But posed against its beautiful and accurate tonality, is an average technical performance. Aspects as separation and resolution are not bad, though not top tier. It’s been mentioned before; when it comes to technical performance, the bar in this shootout is high. Like Aether, Deca is an excellent sounding monitor that deserves more praise than critique – it bests many iems in this shootout when it comes to tone. For many listeners, kindred spirits to Mike perhaps, Deca will hit a sweet spot. But being good at one end of the spectrum is not enough – it needs to excel in all.

Perfect Seal Deca
+Beautiful tonality
+Airy stage
-Bass impact
-Separation and resolution could be greater

The scoring can be viewed in the introduction post.

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