Fidue’s new flagship hybrid: the A91 Sirius



Sirius vs Fidue A83 ($299)
The main question that might be on the mind of many of Fidue’s loyal followers – how does the A83 compare to the new number 1 in line. The Sirius has a wider and taller soundstage, creating an overall bigger screen. In addition, notes are proportionally thicker to the larger stage; the A83 has a more distant instrument positioning. Because both the stage and instrument size is bigger, the sound is fuller and overall more engaging. In addition, the Sirius has better instrument definition.

This fuller sound is due to the more forward midrange, while the Sirius also has more mid-bass emphasis compare to the A83. While the A83’s sub-bass is punchy with bass-heavy tracks, the Sirius has a higher impact overall. The Sirius has a warmer and more pronounced midrange, with more vocal depth; vocals have greater density, and the A83 can sound a bit hollow in comparison. The A83’s signature is tilted slightly more towards the treble, compared to the more mid-centric Sirius; this can make A83’s tone sound a bit metallic in comparison, with a greater tendency towards sibilance. Overall, the Sirius retains the smooth house sound of the A83, while improving in all directions.

Sirius vs. DN-2000j ($299)
The Sirius’ stage is slightly wider, but mostly taller. Both share a quality bass response with nice texture and a natural decay, although the DN-2000j’s has a colder tone compared to the relatively enhanced mid-bass of the Sirius. This gives the Sirius thicker notes and a fuller sound, although the DN-2000j’s stage is cleaner. Compared to the midcentric and more forward presentation of the Sirius, the DN-2000j’s tone is skewed towards the treble. This gives it a high sense of clarity and detail retrieval, while simultaneously making it sound thinner, with a less natural tone.

The Sirius and DN-2000j are tuned with a very different presentation, and overall have fewer similarities than differences. The DN-2000j presents music from an analytical perspective; the Sirius in turn, has a more natural, effortless and fuller presentation.

Sirius vs EarSonics S-EM6 ($950)
The S-EM6 is EarSonic’s contender in the same price range. While it also has a mid-centric signature, it is more midforward than the Sirius. The enhanced mid-bass plays a prominent role, giving a great deal of warmth and size to the midrange. The Sirius’ bass is more neutral and cleaner in comparison, while adding a natural decay from the dynamic driver. The S-EM6 has more of a center midrange peak (around 1kHz), giving vocals more depth and density than the Sirius. Vocals are forward and powerful, and truly the S-EM6’ specialty. Its signature is however tilted more towards the midrange, with less treble emphasis. This gives the S-EM6 a darker sound, taking some of the bite off instruments with a less airier sound overall.

The S-EM6’ stage has similar height and width, but is deeper. This gives the S-EM6 an advantage in its instrument positioning. However due to the thicker notes, the stage doesn’t necessarily feel more spacious compared to the cleaner and relatively more neutral Sirius. The S-EM6 is warmer, thicker and more forward in comparison, but this tends to make it more of a specialist. With its mid-bass and center midrange bumps, the S-EM6 is the equivalent of a curvy, bubblicious woman: there’s a whole lot to love, if it’s your thing. The enhanced bass and warmth won’t be for everyone. The Sirius is relatively more linear in the lower frequencies and cleaner in comparison, with a refined signature that makes it more all-round.

Sirius vs Perfect Seal AR6 ($950)
The AR6 is another great performer with a similar price, also utilising 6 BA’s compared to the hybrid Sirius. The AR6 has a more neutral mid-bass, and greater emphasis on sub- rather than mid-bass. The AR6’ bass hits deep, but is overall lighter and less warm. The AR6’ bass is faster, but it can’t match the natural decay and overall impact of the Sirius. The Sirius’ has overall more bass impact with nicer texture. This contributes to Sirius’ warmer midrange with slightly thicker notes, while the AR6’ stage is cleaner and airier due to it having less mid-bass and lower midrange fill. The AR6’ treble in turn has more sparkle, while the Sirius’ is smoother.

The AR6’ unique selling point is its wide and airy stage; its stage dimensions are both wider and deeper with similar height, and an instrument positioning that is slightly more distant than the proximal placement of Sirius. The AR6 is more spacious, and has the upper hand in separation. While the two iems are very different, they both steer me towards easy listening, singer/songwriter type music. But they take a very different approach, with the AR6’ focus on clarity and sparkle resonating in acoustic instruments, besides its spacious stage. The Sirius on the other hand has that delicious bass, and enveloping warmer midrange better capable of conveying emotion.

Sirius vs EarSonics S-EM9 ($1490)
The Sirius has a slightly wider stage, while the box-shaped stage of the S-EM9 is deeper and airier which gives it an advantage in layering. Both the Sirius and S-EM9 share a bass tuning that is relatively neutral yet exciting; punchy, with good definition. While the BA driven S-EM9’s bass has the better speed, the Sirius brings texture and that beautiful natural decay to the table. The S-EM9 is pretty linear throughout the lower and center midrange, with a dip in the upper midrange giving the S-EM9 a more distant vocal positioning. The Sirius on the other hand has more lower midrange fill, while getting most of its energy in the upper midrange. This gives it better vocal articulation; vocals are more forward and pronounced than with the S-EM9. Due to its slightly mid-centric signature the Sirius also has the warmer midrange, with overall thicker notes.

The S-EM9 has a U-shaped signature with slightly enhanced treble. While the Sirius’ midrange is clearly the more lush of the two in both warmth and size, the S-EM9 displays its refinement in the tuning of its treble, midrange resolution and separation. The S-EM9’s treble extends further, and is more clearly defined. Furthermore the S-EM9 betters the Sirius in its overall speed, the attack and decay. While this gives the S-EM9 a more dynamic sound, it doesn’t say the Sirius underperforms; speed happens to be the S-EM9’s specialty, even compared to other TOTL’s. The Sirius gets points for its overall signature, the excellent bass and midrange. The S-EM9 in turn for its precision in timing and positioning.

Sirius vs Rhapsodio Galaxy ($1600)
As a somewhat ‘exotically’ priced single double dynamic driver, the Galaxy’s bass shares that delicious impact and decay of the Sirius, although the Galaxy’s bass is overall more linear compared to the slightly more enhanced mid-bass of the Sirius. In fact, the Galaxy’s signature is very linear from the bass on through the midrange, only to peak in the lower treble. In comparison, the Sirius is warmer with a more forward upper midrange. Because of this, the mid-centric Sirius sounds enveloping and smooth, while the Galaxy’s tone is skewed towards the treble.

The Galaxy has a more distant stage, with vocals positioned further back in comparison to Sirius. The Galaxy’s stage is slightly wider, but less tall, while the Sirius has a relatively more even proportioning between the width and height of the stage. The Galaxy has the better midrange resolution and cleaner separation due to the relatively more distant instrument positioning, although its stage is also not particularly airy. Taken together, the Sirius tends to pull you in the music with its enveloping midrange placed closer to the listener, with a focus on a natural and smooth tonality. The Galaxy’s presentation is more distant and flatter, although instruments are better defined with an overall higher level of detail.


Concluding thoughts

The Sirius has a slight mid-centric signature, but it’s ever so well balanced. The sound isn’t too forward or thick, while having the right amount of warmth to sound natural. The treble is inoffensive, which means it can be played for days on end. It’s a type of signature that drifts me towards band-based music, soothing guitars and beautiful vocals. Its tuning is very mature, and seems designed to please all types of listeners in the market. With the Sirius, Fidue has delivered an excellent addition in the sub $1000 segment. With its natural and smooth midrange it has its own strengths, even compared to higher end monitors. The delicious bass is just a bonus at this point.

Whether or not Fidue is publicly stating it, they are implicitly sending a message; high quality is possible for a (relatively) affordable price. They’ve shown they can do it in the affordable segment, and they’re taking it to a higher level now with their all new flagship. The modular system is a very nice extra. With the lower regions of the market covered, they’re coming for more. As a complete product, the Sirius oozes with class; the design, packaging and distinguished tuning.

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About Author

Nic is currently in pursuit of a PhD degree in social neuropsychology, while trying not to get too distracted by this hobby. In pursuit of theoretical knowledge by day, and audiophile excellence at night. Luckily for him, both activities are not mutually exclusive which helps to lighten the workload. Always on the go, Nic's enthusiasm for hi-fi is focused on all chains of the portable system: iems, cables and daps.


  1. Can you compare Sirius A91and earsonics Velvet? How do they fare against Perfect deal AR6/deca? I’m more keen on learning the comparisons of staging, imaging and instrument separation.
    Thank you.

    • Please excuse my late response, didn’t notice it for a while. The Velvet has an opposing signature, with a laidback midrange and enhanced treble and bass. The Velvet’s midrange is distant and a bit hollow in comparison to the more forward and warmer midrange of the Sirius. It does however offer more clarity and excitement in the upper frequencies. The Sirius sounds a bit warmer/darker, with a more emotional tone for instruments and vocals. Both have wide stages, though not particularly deep. The A91 has a bit taller stage, but this is going off memory. Velvet was more of a flat/wide stage. Simply put, I’d highly recommend the Velvet for V-shaped genres like pop, hip hop, electronic music. I’d go with the Sirius for instrument-based and vocal music.

      The AR6 and Deca have a more neutral tuning, with a lighter/clearer sound, as they peak in the upper midrange around 5 Khz where the Sirius dips. All of them have a nice stage, with the AR6 having the most spacious and airy sounding stage, and the A91 and Deca being more similar in proportion. The Deca has a very natural tonality, but is a bit soft in the mid treble region, so it’s not necessarily pin point analytical precise when it comes to imaging. Going off memory, I’d say the AR6 has an advantage in its stage and separation, it was a discerning feat. But it was quite a while since I heard it.

      Let me know if you have any more questions.

      • I’m sorry if this question is a bit weird. If you had to live with one IEM to fulfill all your music needs taking into account all your personal preferences (tonality, staging,comfort, source dependency etc.), in what ways would the perfect seal AR6 be deficient? And which is that one IEM you would choose?

        • Well it’s a perfectly normal question 😉 The AR6 was too light on bass for me. I’m not a basshead, but I do appreciate bass a little bit north from neutral; nice sub-bass impact, and a mid-bass that gives some rhythm and fullness to the music. The AR6′ bass extends deep, but for iem standards it was below average in quantity.

          It’s hard to pick one as I listen to very different genres, and in most case an iem is a bit of a specialist for one but performs worse on others. I like Zeus-XIV and the NT6pro, they’re kind of opposites. I’m currently listening to Deca, is a very natural sounding ciem with more mid-bass quantity than the AR6. Andromeda is a nice allrounder at an honest price.

  2. Can you compare earsonics Velvet and Sirius ?
    If you had to live with only one earphone which one would you choose between Perfect seal AR6, Velvet and Sirius? 🙂

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