Fidue’s new flagship hybrid: the A91 Sirius


S3Sound Impressions

The Sirius has a well-balanced signature with a mid-centric focus. A hint of warmth that adds an emotional touch to the music, without overdoing it. The instrument positioning is slightly close to the listener, with the vocals placed a bit further behind. Because of the proximal front line positioning spanning along the width, the stage has a bit of a ‘front row’ effect where you’re close to the music. The instrument size is well proportioned within the stage; neither thick nor thin – just exactly right, which gives a nice sense of spaciousness. The stage is wide and has good height, creating an overall large screen. In my initial impressions with the Cowon Plenue S I found that the Sirius lacked some depth, but this is source dependent as the Lotoo Paw Gold provides more depth and air, at the cost of some of its width. On the other hand, the Sirius’ tonality comes across as more natural with the warmer Plenue S, mainly due to a more prominent and brighter upper midrange with the Paw Gold.

The bass is fairly neutral, with a slight emphasis on mid- over sub-bass and an overall warm tone. The sub-bass is a pure delight. I spend most of my time listening to multi-BA drivers, so the gorgeous ‘thump’ of a dynamic driver is refreshing. That texture and decay; it’s with good reason people say a BA can never deliver that same type of quality. Kick drums sound magnificent, very realistic due to that decay. Not to mention bassy electronic music – possibly with the bass amped up a bit. I believe the proper audiophile terminology for this would be ‘awesome’. The mid-bass is well-controlled, although there is a tradeoff for speed compared to faster BA drivers. Overall the bass is punchy, textured with a natural decay, and I rate it highly.

The Sirius has a beautiful and sweet midrange, alongside the nicely textured bass. Slightly forward, but mostly balanced and refined, a tuning I liked from the go. The midrange is warm and smooth, with a natural timbre for vocals and instruments. In accordance with its mid-bass it has a slight lower midrange fill, giving the Sirius the right amount of note thickness without overdoing it. The midrange emphasis is on the upper midrange; guitars have good bite and vocals are clearly articulated, though not as deep or dense as a truly midforward iem as the S-EM6 or Zeus-XIV that have an emphasis on the center midrange. This gives the Sirius an excellent sense of balance, as vocals are neither particularly forward nor distant. The upper midrange peak is followed by a dip around 4-5 khz which adds some fullness to the presentation, adding to the overall smoothness rather than artificially brightening the midrange. Its midrange resolution is good within its price tier.

The treble takes a slight step back in the presentation, giving the Sirius a smooth and more mid-centric signature. A lower treble dip is followed by a peak around 7 kHz; a common tuning in many iems. It’s a necessity to add some clarity, especially in a mid-centric signature that might get too stuffy otherwise (we’ve seen this recently in the Primacy). The peak gives an iem a more ‘hi-fi’ sound, although there is a tradeoff for tonal naturalness at higher volumes. With a treble rolloff around 10 KHz, the Sirius performs according to the iem average. The treble is foremost smooth and non-fatiguing, and tends to stay on the safe side of sibilance. Overall, I’m a bigger fan of the bass and midrange; the treble is there doing its thing, but lacks that final bit of precision. This isn’t a treble that will bother anyone, but it doesn’t excite me much either.

S1Page 3: Comparisons and conclusion

1 2 3

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? 🙂

Reply To Vel Cancel Reply