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My first foray into the world of quality sounding IEMs was with Shures range quite a few years ago – starting with the SE425 and culminating with the SE535LE. From there I first experimented with hybrid IEMs – first T-Peos Altone 200 and Dunu's DN-1000 triple drivers, and shortly afterwards Fidues A83 triple. The A83 mesmerised me, and the sound still captivates me when I get them out from time to time. What impressed me was the big sound – the robustness of the bass, but also the way Fidue approached their mid-range. It was something I hadn't encountered before – undoubtedly coloured and mid-forward, but in a really good way. My one issue with the A83 long term was its longevity (build). I had issues with the connectors – but otherwise it was a great IEM.
So when Fidue approached me about reviewing their flagship (Sirius / A91) I was naturally both intrigued and also hopeful. Could Fidue improve on the A83's signature, and also produce a flagship with genuine build quality?
Fidue Acoustics is a Chinese earphone company founded by Benny Tan (who has more than 20 years design experience – developing earphones for other global branded companies). The name Fidue is simply an acronym of the principle design points that the company strives to implement in their product range
From their website “The guiding principle of FIDUE Acoustics is reproducing original sound accurately, and maintaining clarity, dynamics and natural expression.”
Fidue have a full product catalogue including single dynamic driver IEMs in the budget sub $30 range to hybrids – which now include their new TOTL flagship – the Sirius A91. The can be found at Facebook HERE, or their product range viewed at their website HERE.
The Fidue A91 Sirius that I’m reviewing today was provided to me gratis as a review sample. I have made it clear to Fidue that I still regard any product they send me as their sole property and available for return any time at their request. But I thank them for the ability to continue use of the Fidue A91 for follow up comparisons. I do not make any financial gain from this review – it is has been written simply as my way of providing feedback both to the Head-Fi community and also Fidue themselves.
I have now had the Fidue A91 since late 2016. The retail price at time of review is USD 899, and can be purchased via Penon Audio.
PREAMBLE - 'ABOUT ME'. (or a base-line for interpreting my thoughts and bias)
I have very eclectic music tastes listening to a variety from classical/opera and jazz, to grunge and general rock. I listen to a lot of blues, jazz, folk music, classic rock, indie and alternative rock. I am particularly fond of female vocals. I generally tend toward cans that are relatively neutral/balanced, but I do have a fondness for clarity, and suspect I might have slight ‘treble-head’ preferences. I am not treble sensitive (at all), and in the past have really enjoyed headphones like the K701, SR325i, and of course the T1 and DT880. I have a specific sensitivity to the 2-3 kHz frequency area (most humans do) but my sensitivity is particularly strong, and I tend to like a relatively flat mid-range with slight elevation in the upper-mids around this area.
I have extensively tested myself (ABX) and I find aac256 or higher to be completely transparent. I do use exclusively red-book 16/44.1 if space is not an issue. All of my music is legally purchased (mostly CD – the rest FLAC purchased on-line). I tend to be sceptical about audiophile ‘claims’, don’t generally believe in burn-in, have never heard a difference with different cables, and would rather test myself blind on perceived differences. I am not a ‘golden eared listener’. I suffer from mild tinnitus, and at 49, my hearing is less than perfect (it only extends to around 14 kHz nowadays). My usual listening level is around 65-75 dB.
For the purposes of this review - I used the Fidue A91 Sirius straight from the headphone-out socket of most of my portables. I did not generally further amp them (I did test them with my E17K, A5 and IMS HVA), as IMO they do not benefit greatly from additional amplification (YMMV and it may depend on your source). In the time I have spent with the Fidue A91 Sirius, I have noticed no change to the overall sonic presentation (break-in). Time spent now with the A91 Sirius would be easily 200+ hours.
This is a purely subjective review - my gear, my ears, and my experience. Please take it all with a grain of salt - especially if it does not match your own experience.
PACKAGING AND ACCESSORIES
|Front of the retail box||Rear of the retail box|
“Sirius is the brightest star in the universe. The ancient Greeks believed that it was the guardian of the road of the soul and an omnipotent hunter”.
|The inner box||The A91 Sirius nestled safely in the top tray|
|The cable adaptors and manual||Bottom layer with storage case|
- 4 pairs of black silicone tips (XS/S/M/L)
- 1 pair of medium T500 genuine Comply tips
- 3.5mm Female to 6.5mm Male Adapter
- Airline adaptor
- Anodised aluminium storage case (large)
- Cleaning tool and disassembly tool
- Maintenance and warranty card.
- Fold-out booklet/manual
- 1 x 2.5 mm balanced to MMCX earphone cable
- 1 x 2.5 mm balanced to 3.5 mm single ended short adaptor cable
- 1 x 2.5 mm balanced to 3.5 mm balanced short adaptor cable
|The storage case||Accessories inside the storage case|
|Main cable, standard adaptors, comply tips and tools||The A91 Sirius, cable adaptors and silicone tips|
(From Fidue’s packaging / website)
|Approx price||$899 USD (Penon Audio)|
|Type||Five driver hybrid IEM|
|Driver - Dynamic||1 x 10mm titanium DD|
|Driver - BA||2 x Knowles dual BA (4 BA)|
|Freq Range||4Hz – 45 kHz|
|Cable||1.3m, replaceable (MMCX)|
|Jack||2.5mm rhodium plated balanced, straight – with adaptors|
|Weight||37g with default cable|
|Casing material||Anodised Steel|
The graphs below are generated using the Vibro Veritas coupler and ARTA software. Ken Ball (ALO/Campfire) graciously provided me with measurement data which I have used to recalibrate my Veritas so that it mimics an IEC 711 measurement standard (Ken uses two separate BK ear simulators, we measured the same set of IEMs, and I built my calibration curve from shared data). I do not claim that this data is 100% accurate, but it is very consistent, and is as close as I can get to the IEC 711 standard on my budget.
The graphs are provided merely as a point of discussion, and later in the review I've included comparisons to other IEMs for similar reference.
|A91 Sirius frequency and channel matching||A91 Sirius – vent unblocked vs vent blocked|
My sonic impressions of the A91 Sirius – written well before I measured:
- Bass performs well (sub and mid-bass), reaches low but is not over-emphasised. There is audible sub-bass rumble, so bass extension appears to be pretty good.
- Lower mid-range is not recessed at all, and male vocals are well represented.
- Upper mid-range is emphasised, and it is a definite colouration, but one I appreciate. Female vocals have a wonderful sense of euphony, and the bump gives very good clarity without losing overall tonality
- Lower treble extension is good – but there appears to be some roll-off above about 7 kHz. Cymbal fundamentals are pretty good – but the decay is ever so slightly truncated (hardly noticeable in most tracks). It does contribute to a clean and clear sound though, and one that is thoroughly enjoyable.
- Overall a well balanced earphone with an upper mid-emphasis
- Channel matching is excellent
|Internal side of the shell||Front (internal) and top|
|External side of shell||Rear and view of sockets|
|MMCX socket and male connector||(right) default cable fully connected, (left) CA Tinsel cable|
|Y-split and cinch||2.5mm balanced jack|
The cable system is heavy duty, modular, and one which will see some people loving it, and others perhaps not so endeared. The main cable is 1.3m long and consists of a very flexible braided 8 core SPC cable which is nylon covered throughout. As such it is extremely strong, and so far for me has been surprisingly hard wearing (I expected some fraying, but so far, so good). It has not been prone to tangling – but is somewhat bulky. So far – hooked over the ear, and worn under and outer layer of clothing, it is quite free of microphonics. The Y-split is the same lightweight metal alloy of the main body, well relieved and has a very good cinch in-built which works really well.
|Modular adaptors||3.5mm balanced adaptor connected|
|The A91 Sirius – aesthetically stunning||And versatile – paired with my iPhone and Bluetooth adaptor|
FIT / COMFORT / ISOLATION
I'll start with the easy one (isolation), and we can then look at fit and comfort. Isolation is dependent on tip selection, and if you get a good seal, it is actually pretty good (about average for a vented hybrid IMO), but will not ultimately reach the high isolation of sealed BA IEMs. It would still be reasonably good for a busy street, or some forms of public transport though – although wouldn't be my personal choice for long haul flights.
Now we get to fit and comfort – and these thoughts are more subjective. As I said above, the Fidue A91 Sirius has an ergonomic body shape, with a good length of slightly angled nozzle, and for me personally they are extremely easy to fit – but the nozzle is relatively shallow in-ear. They are designed for over-ear use. Anyone used to ergonomic BA designs should have no issues. They are also quite comfortable for everyday use …… but with a small note. When I first wore the A91 Sirius I would experience some discomfort with a single sharp edge. It wasn't a huge problem – but I knew it was there. The issue for me was simply that I wasn't use to the the sharper angle reacting with my intertragical notch, and because I have bigger ears, I could feel the flat external edge against my skin. The answer was in my choice of tip (Shure Olives), so I could adjust the A91 Sirius so that the pressure there was relieved. It also took some time for my ear to get used to the angle. Nowadays, I can wear the Sirius for hours – and find it very comfortable. But for Fidue – this may be a point worth noting. Neither would be an issue with some rounding of the juncture of the top external plate, and also a less acute angle at the front. Another thing which may help is an extra couple of mm length on the nozzle.
|Spinfits and foam tips fit well – others not so good||My preferred Shure Olives|
|Part of the issue is the lipless nozzle||But fit for me is still pretty good|
So the overall build is brilliant, and the design could be improved slightly, but again extremely good and well thought out.
The following is what I hear from the Fidue A91 Sirius. YMMV – and probably will – as my tastes are likely different to yours (read the preamble I gave earlier for a baseline). Most of the testing at this point (unless otherwise stated) was done with my FiiO X5iii (single ended) and also the X3ii + E17K combo, no EQ, and Shure Olive foam tips. I used the FiiO devices simply because paired they give me a very transparent window to the music with low impedance, and more than enough power. With both, their was no DSP engaged.
|My trusty FiiO X3ii + E17K||And the very classy FiiO X5iii|
- Sub-bass – has good extension and even at my low listening levels is audible, but there is no boosted emphasis and it sits extremely well within the overall frequency mix. There is enough rumble to give presence without overshadowing vocals, and I'm detecting no bleed into lower mid-range. Lovers of elevated lower bass frequencies would need to EQ or play with partially blocking the bass port.
- Mid-bass – pretty linear compared to lower mid-range and to my ears sounds quite natural but with no real emphasis. Slightly more mid-bass than sub-bass, but neither is really emphasised. Any mid-bass hump would be very slight. This reminds me very much of original HD800 type mid-bass – enough to sound tonally natural and give very good overall timbre, but again its relatively linear or flat rather than emphasised.
- Lower mid-range – no recession compared to bass but quite a bit lower than the upper mid-range peak around 2 kHz (about 10 dB). Vocals don't appear overly distant though, and this is fantastic – especially when you consider the overall cohesion between lower and upper mid-range for vocals. Male vocal in particular have a reasonable amount of body, but there is definitely more emphasis with female vocals.
- Upper mid-range – elevated compared to lower mid-range, and there is a rise from 1 kHz to the main peak at 2 kHz. The result is a clean and clear vocal range, with extremely good overall cohesion and some real euphony for female vocals to sound sweet and elevated. This is probably the most coloured part of the entire frequency range – but especially for female vocal lovers, it is a colouration I really like.
- Lower treble has less emphasis overall and the only real peak is at 6-7 kHz and this is actually slightly less in amplitude than the upper mid-range. There is simply very good overall detail and clarity – but without too much etch or grain which some other IEMs overdo by trying to hard. Overall this area does not over-emphasis simply because the bass is so linear.
- Upper treble – rolls off – but does not affect/detract from the overall signature.
- Really excellent overall clarity, and this was especially so on older recordings (10cc's Art for Art's Sake) where some of the detail can be lost when bass bleed over shadows. The Fidue A83 simply goes about it's business – but without having to spotlight or overemphasis lower treble.
- Cymbal hits have very good clarity and overall presence, and while they also have very good decay – there is a very slight hint of truncation which I don't get from the likes of the Dunu DK-3001 . This really is nit-picking though, and only noticeable if you are critically listening for it
- Overall I feel as though I'm hearing everything in the recording – and this is even at my lower listening levels.
- Directional queues are extremely good – very precise, and presentation of stage is definitely beyond the periphery of my head space with binaural tracks – so really good sense of width and depth. This (pleasantly) surprised me a little because I expected with the upper mid-bump for this to be less pronounced.
- Spherically presented sound-stage – no issues with L/R dominance
- There are very few IEMs which manage to totally immerse me in the audience with the applause section of “Dante's Prayer”. The Fidue A91 manages it easily, I'm there in the audience, and you can't get much better than that with an IEM. Easily as immersive as my U6, and I had to actually check to make sure that the Viper settings were disengaged on the X5iii. “Let it Rain” was my next track and it was again brilliant (very 3D like experience - the way the track was miked). There was the slightest hint of sibilance with Amanda's vocal – but again, its the way it is recorded – so not unexpected. What was great is that the sibilance was actually quite subdued, but the detail still shone through clearly.
- Overall tonal balance and clarity – while retaining a very smooth sonic presentation
- very good sense of stage and imaging
- Detailed at low listening levels
- Reference sound with slight colouration or forwardness in upper mid-range area. Transition between lower and upper mid-range is extremely good.
- While I personally don't find it to be a weakness – some may find the bass to be a little linear. This could also depend on overall fit and anatomy.
The Fidue A91 Sirius doesn’t need amplification for overall volume – and because its impedance isn't spectacularly low, any source with an output impedance of less than 3 ohms should pair OK. All of my sources are pretty low OI and I had no issues with tonality changes. I don't tend to notice hiss (older ears) – so no real issues for me with the Sirius. The interesting thing with using the X5iii is that despite the balanced output being around 3 ohms (SE is lower), my daughter noticed no hiss – even at maximum volume (no music playing of course!)
|Testing with the IMS HVA and FiiO A5||Balanced with the SuperMini|
RESPONSE TO EQ?
In my opinion the A91 Sirius sounds beautiful with its default tuning, and I wouldn't personally feel much need (if any) for EQ. However I know that some may like more warmth and more bass impact, and this was easy to check with the X3ii and E17K combo. I used “Art for Art's Sake” again, and simply added +4 bass with the E17K. The resultant tonality was very good, and still did not detract from the clarity. I then took a much warmer recording (Dido's “Girl Who Got Away”, reduced the bass to neutral and added +4 treble. Again the change was immediate but really well presented. The A91 Sirius responds well to EQ, although again I am really happy with its default sonic signature.
BALANCED VS SINGLE ENDED
Having the balanced cable option is nice, but I noticed no real change with the likes of the X7 + AM3 module once I had properly volume matched (using the Fidue A91 cable adaptor for fast switching). Personally I wouldn't be able to tell the two apart in a blind test. For those with DAPs where the balanced sounds better (different circuitry), its nice to have the option though.
COMPARISON WITH OTHER IEMS
These comparisons were all done with the X5iii, (no EQ or DSP) – and volume matched using a calibrated SPL meter and fixed 1kHz test tone first. Choosing the comparisons, I wanted to firstly compare against the former Fidue flagship (A83), and then with IEMs of similar ability and price range. This is always more subjective than objective, and I don't personally have access to a lot of IEMs around the $500+ mark. So I ended up comparing with the $300 Fidue A83, DUNU's new ~$500 DK-3001, Rhapsodio's older ~$800 RTi1 single dynamic, and 64Audio's ~$900 U6 and ~$1400 U10. Hopefully this gives enough insight to anyone interested in this IEM. Here are my very subjective personal thoughts:
Fidue A91 Sirius (~USD 900) vs Fidue A83 (~USD 300-340)
|Fidue A91 Sirius and Fidue A83||Frequency comparisons|
Overall sound quality firmly is in favour of the Sirius also (as you'd probably expect). The A91 has a much more balanced signature – and when Fidue describe it as “reference”, I can clearly both hear and see that this is the case. The A83 has more of that usual V-shape associated with a lot of hybrids, and the bass is more pronounced – but also boomier. The other big factor with the A83 is that the pronounced peaks also tended toward some grain in both upper mids and lower treble. I loved the clarity when I first reviewed them, but over time, and when comparing to more balanced signatures (DK-3001, Andromeda, and especially the Sirius), I've come to appreciate clarity without the peaks. The Sirius is a definite and definitive upgrade in virtually all areas, and IMO worth the upgrade and additional asking price.
Fidue A91 Sirius (~USD 900) vs Dunu DK-3001 (~USD 470-500)
|Fidue A91 Sirius and Dunu DK-3001||Frequency comparisons|
Sonically there are some similarities. Both are well balanced earphones in their own way – the DK-3001 having the more traditional shallow mid-bass hump, moderate dip in lower mid-range, and more extension through the lower and upper treble. Both have an upper mid-range emphasis. Where the DK-3001 shines is in its overall signature balance and extension throughout the frequency range. The Sirius accomplishes the same goals through different methods – a little less bass which allows the mid-range and lower treble to be well focussed without needing any further emphasis. I love both earphones for their signatures, and it is actually quite difficult for me to pick a preference on sonics alone. For my own personal preferences I've always appreciated a slightly cleaner and cooler sound - and for me personally the Sirius delivers this slightly better, but I could definitely see opinions being divided.
There is a big difference in overall cost between the two. If the cost wasn't a factor I'd lean towards the Sirius as a personal preference – but both are truly excellent sounding monitors, and if bang for your buck is a factor then the DK-3001 more than holds its own.
Fidue A91 Sirius (~USD 900) vs Rhapsodio RT1i (~USD 800)
|Fidue A91 Sirius and Rhapsodio RT1i||Frequency comparisons|
Sonically there are a little more differences this time, with the RT1i being a
far more V shaped monitor with a definite upper-mid/lower treble peak centered at 5-6 kHz. Comparatively the RT1i delivers a fun sound which I still very much enjoy, but there is some heat which comes with some definite sizzle (personally I prefer it EQ'd down a little), and vocals have a little more distance. And it doesn't take a lot to correct this, but up against the more balanced and better finished Sirius, for the $100 difference it would be an easy decision for me. The Fidue Sirius is simply a better presented overall proposition.
Fidue A91 Sirius (~USD 900) vs 64 Audio U6 + G1 ADEL module (~USD 900)
|Fidue A91 Sirius and 64 Audio U6||Frequency comparisons|
Build quality (materials) is firmly in the Sirius favour. Its going to last for quite some time with the use of the alloys and quality of the cable. You'll note with my U6 that I'm using the Linum Bax cable and thats because my 2nd 64Audio cable has broken at the 2 pin connector. I know 64Audio would have replaced it – but this time I wanted a longer lasting solution. Accessories remain with the Sirius – but the U6 has the ADEL modules and ability to tune. Fit and comfort is slightly in favour of the U6 – the ergonomic build is simply slightly more comfortable for me.
Once again we see a similar pattern – the Sirius has more linear bass and a flatter overall signature, while the U6 has the gentle V and more natural mid-bass hump. With the G1 module, both have a bump in the upper mids, but the U6 has more lower treble extension, and to be fair, needs this to counter the increased bass. Both are incredible monitors, and the main difference is the added warmth of the U6 – which again makes the Sirius a little cooler and cleaner comparatively. Ultimately this will come down to preference as both sound gorgeous. The interesting thing was (using E17K's tone controls as EQ) simply taking the U6's bass down by -4, and already it managed to drop some of the warmth out of the U6 – and get the two much closer. For me personally I still have a slight preference to my U6, but ultimately this comes down to the time I've spent with them and my own personal preference. If I only had the Sirius I would not at all be disappointed.
Fidue A91 Sirius (~USD 900) vs 64 Audio U10 + G1 ADEL module (~USD 1300)
|Fidue A91 Sirius and 64 Audio U6||Frequency comparisons|
Build quality (materials) is again in the Sirius favour for the same reasons I outlined with the U6. The Sirius also takes the win for overall finish, quality, and accessories. The U10 wins on comfort, and also it has the benefits of tunability with the ADEL modules, and also has other benefits with the modules (they really do help with lowering my tinnitus issues).
Like the U6, we see a similar pattern – the Sirius has more linear bass and a flatter overall bass signature, while the U10 has the more natural mid-bass hump. With the G1 module, both have a bump in the upper mids, but the U10 has more lower and upper treble extension. Again the main difference is the added warmth of the U10 – which again makes the Sirius a little cooler and cleaner comparatively. I again tried dropping the bass response on the U10 down with the E17Ks tone controls and I was genuinely surprised at how close the two monitors perform. The Sirius still sounds a touch cooler and cleaner, but at -6 bass on the tone controls there is not very much difference between the two (and if anything I really like this new tonality on the U10).
So this goes to show that the Sirius is indeed flagship material, and definitely belongs in the same class with the newer $1K family of monitors becoming more prevalent. Which did I prefer? Well its really too close for me to call – and depends on the value you put on the ADEL system. For me personally its worth it (the price difference) but without having access to the U6 or U10, I could quite easily settle with the Sirius. It genuinely is that good.
FIDUE A91 SIRIUS – SUMMARY
Despite having these for more than 6 months, its surprising when you sit down for a formal review that you still discover new overall strengths in monitors you thought you knew.
The Fidue A91 Sirius is every bit the TOTL reference IEM which Fidue intended it to be, and I've come to appreciate its strengths even more over the last couple of weeks of critical listening.
Starting with build, design and quality of materials used – Fidue has really lifted the bar from their previous A83. Design and finish is up there with the best, and their new locking MMCX connectors are a great solution to some of the issues formerly with the A83. The modular cable system is also somewhat of a novel approach to managing consumers desires for different balanced and SE connectors – and actually works pretty well.
Sonically the Sirius is extremely well balanced with a largely linear frequency response coloured a little with a bump in the upper mid-range (which personally I really like). The result is a very clean and clear tonality, albeit with a slightly cooler or leaner overall lean. And while bass is linear, it is still beautifully presented and definitely present when called upon.
The RRP at around the USD 900 mark means that this is a reasonably large investment in an IEM but if you appreciate this sort of tonality I can honestly not think of a lot which will deliver this sort of total package. Despite the price point, I would still recommend them wholeheartedly – they just sound too good not to. For my part, I'd still love to see them get the ergonomics 100% right and a return to a lipped nozzle (and maybe slightly longer too) which would really complete an otherwise excellent monitor. For me a 4.5/5 or 90% review ranking.
I just want to close with thanking Michael for arranging the review sample, and apologise for taking so long with it.