Fidue A31s – Review

Fidue A31s

Fidue A31s

| 8 mm MicroDriver |

? Fidue is an Asian earphones and headphones company with a vast catalog of models with very good acceptance in the audiophile world for their higher range models. Fidue has classified their earphones in 4 categories with these names: Reference level, Audiophile level, Entry level, Music & Entertainment. The Fidue A31s belongs to their “Music & Entertainment” category. The Fidue A31s have a very unique design as you can see from the photos, their size is minuscule and ultra light weighted. Despite their tiny sized housings inside they hold an 8mm dynamic driver, which is outstanding how they were able to fit a fairly sized DD in such a small earpiece. The dynamic driver is placed sideways instead of the classic frontal positioning, we have seen this kind of design previously in our review of the marvelous Sony MDR-7550 / Sony MDR-EX800st. The housings are made of a translucent plastic that allows you to easily see the inner dynamic driver. Regardless of their construction material they feel rugged and durable enough. The cable has a textured feel to the touch and some rubberized finish to combat tangling issues. The problem with the cable is that it does not ever straighten up, it remains with the “wrapped-form”. There is an inline mic/control with a single button that allows to skip songs, play/pause music and answer/reject calls. You can buy the Fidue A31s in a variety of colors: white, red, yellow or green.

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Fidue A31s - Review

Tests & Scores




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Accessories & Packaging

The packaging of the Fidue A31s is simple and similar to the one of the Einsear T2, but larger. Inside you will get a hard plastic carrying case, a pair of cable guides, a cable clip, 3 pairs of earips and 1 pair of double flange deep fit eartips.


Fidue A31s - Accessories
Fidue A31s – Accessories


Bass & Sub Bass

The ultra small size of the Fidue A31s inspires little confidence regarding bass response, instead, this minuscule earphones will surprise you with a highly strong punch and deep bass personality. Truly, their bass is very respectable and jaw dropping if the housings size is taken in consideration. Any bass requirements will be covered by the Fidue A31s with no issues at all, they will provide all the fun and energy needed for any type of music genre even if they are pushed through highly bass hungry songs. An EQ added a noticeable increment of mid-bass and sub-bass. Running them though our extreme bass tests by setting a custom basshead EQ and amplifying them with a Fiio E12 Mont Blanc with it’s bass boost turned on and set to high gain, the Fidue A31s were capable of handling 50% of the Fiio’s maximum power, which is an insane amount of power that they were able to take. As a result there was a huge increase in mid-bass punch and sub-bass depth reaching basshead impact and rumble above the Xiaomi Mi Pro HD and the KZ ATE, you can expect a basshead level below the Xiaomi Mi Quantie Pro Hybrid and in the range of the Elecom EHP-CA3580.


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Mids & Vocals

The mids of the Fidue A31s have a very warm sound and recessed lower mids with lower vocals sounding somewhat congested at times due to a strong mid-bass bleed, higher mids are not harsh but rolled off too. People liking very warm mids and who prefer warmth to clarity might like their mids. With an EQ lower vocals sounded less distant but still with a recessed overall feel; higher mids remained free of harshness.



Highs & Treble

The highs of the Fidue A31s are dark with a low level of brightness and no detail. Piercing and sibilant highs are not present. Applying an EQ, sibilance remains under control, piercing highs can show up with strong notes and some brightness and detail is gained.


Fidue A31s
Fidue A31s


Sound Leak

The sound that leaks out of the Fidue is low and 100% usable in most situations with no fear of making your listening sessions public to nearby people unless you set a very high volume.



Sound Isolation

The sound isolation performance was outstanding, with a very strong reduction of perceivable surrounding sounds even when using a moderate volume, the double flange eartips help them to achieve this level of isolation.




With their tiny housings and feather weight they are very comfortable to wear and can be used for several hours with no discomfort.



Response to Equalization

The Fidue A31s had an average response to EQ, some improvements were noted but overall nothing drastically improved. Bass had a stronger response after an EQ (though certainly not needed); mids benefited from less distant lower vocals but still were unable to get free of the general recessed sound; highs added brightness and detail to some extent but they kept sounding dark.


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Frequency Response (raw)

Fidue A31S Frequency Response

Fidue A31S - Frequency Response
Fidue A31S – Frequency Response

Fidue A31S


Driver Unit8mm
Power Capacity20mW
Impedance19 ohms
Frequency Response18-20,000Hz
CordY-type, round cord
Cord Length1.2m
PlugL shaped stereo mini plug
WeightApprox. 10.7g
Supplied Accessories3x Earphone tips; 1x double flange eartip; 1x cable guide; cable clip; carrying case

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We highly discourage anyone from trying to apply our testings to your own earphones, the risk of damaging or permanently breaking your iems is absolutely probable to happen. With our standardized equalization and amplification tests we push the limits of the earphones to the extreme. If anyway you decide to do so, we cannot be held responsible of the damage done to your equipment. Do it at your own risk.

Fidue A31s