Fosi Audio DS2 (2024 Cirrus Version)

FOSI AUDIO is an audio company that quite reflects its solid reputation as an audio brand whose products offer exceptional sound quality, superb performance and good build quality at affordable price for budget-conscious audio enthusiasts. This audio company offers a variety of products from desktop preamps up to DAC/amp USB dongles. I actually publish some reviews of their products before and you can check it out at the end of this assessment



What I have here that will be featured here in this review content is their latest DAC/Amp USB dongle, The FOSI AUDIO DS2. Like most DAC/Amp dongles that were available in the market, this device follows its usual form factor like elongated rectangular structure, a metal alloy chassis, type-C port and different types of audio jack interfaces.



As I mentioned that it has a metal alloy chassis, it seems that it underwent a CNC-milling process to achieve that uniform construction to have a firm and solid build with a sand-blasted finish on its surface in a gunmetal colour scheme to exude that premium-feel while maintaining a lightweight profile. Among the USB DAC/Amp dongles that I've tested, The FOSI AUDIO DS2 is probably the most compact size with a good balanced weight on it.



In both ends, it has a USB type-C port while its opposite side, that's where the two types of headphone port interface are situated, the 3.5mm single ended and 4.4mm balanced output. On the side panel, there are volume key buttons for volume control which have independent functionality depending on a music player app's settings.



At the top panel, there's a RGB LED indicator for sampling rate and type of digital audio format.



Here are the following colour-coded display:



Regarding its internals, it uses an older generation of Cirrus Logic, the CS43131 in a dual configuration. This DAC/Amp is a 32-bit 2-channel audio DAC that can decode up to 384KHz sampling rate on PCM and DSD256 on DSD format which makes it a high performance audio chip. This particular audio chip is actually very reliable and very power efficient to deliver a hi-fi sound with low distortion, high signal-to-noise ratio and better dynamic range to deliver a clean, transparent and stable sound quality. The built-in amplifier of this IC has a maximum power output up to 2Vrms which is enough to drive some of the most power-demanding headphones out with an impedance of 600 ohms.



This device has a detachable type-c to type-c short cable and its wiring strands are twisted.

Regarding its product packaging, FOSI AUDIO DS2 is very simple with meagre inclusions.



Here are some contents inside of its packaging box:

• FOSI AUDIO DS2 dongle
• Type-C to type-C cable
• User's manual
• USB type-C to type-A adaptor

Regarding its hardware and software compatibility, this device can be used on devices such as smartphones, tablets, laptop and desktop. And for software, it can support both desktop and mobile operating systems. Windows, Mac OS and Linux on desktop OS, and then Android and iOS on the mobile OS although in older iPhone models, you need a lightning to type-C cable. In Android OS apps, there are few music player apps that can support USB audio access to bypass the android OS audio sampling like Hiby Music App, UAPP (USB Audio Player Pro), Neutron App and Onkyo HF player.



As for its tonal profile, it seems that like almost all devices with Cirrus Logic DACs, this device has a warmish-neutral sound that it has a tad textured lows and mid frequency and a rather linear high frequency which makes this set more appealing to audio enthusiasts who wants a more analogue-ish sound signature.




LOWS/BASS:

This device is capable of delivering a well-defined punchiness, tactual and slamming bass response even if it was paired with more neutral-sounding sets with tighter and lightly thump bass, it can add some texture to it.

It can give a satisfying deep rumbling and reverberating sub-bass presence generated from instruments such as low tone bass guitar, bass violin, synthesisers and drum machines. It adds some density on note weight that might affect the tonal colour and characteristics on some instruments like bass trumpets, bass guitars, viola, bass clarinets, bass kick drum and a particular type of male voices like bass and bass-baritone vocals.


MIDRANGE:

The midrange quality of this one is quite well-textured as it has a hint of warmth that gives some depth and volume of vocals and instruments to sound at least more natural. Another thing that I also observe is that it has some transparency and a tinge of energy that will be more convenient on some female vocals, then a hint of crisp and brill on strings and woodwinds.

On male vocals, baritones have some smooth and plush sound while tenors have brassy and clear vocals. Countertenors have this opaque, coppery and tender vocals which share similar tonal characteristics with female mezzo-sopranos. Contraltos sounds almost correct on this one as it has a sufficient amount of richness and hefty on its vocal quality and then on sopranos, it has creamy and silvery that makes them even more captivating and mesmerising to listen to.

As for instruments, it sounds quite natural with a good amount of detail and clarity. On string instruments, there's a balanced to meaty sound on the guitars especially on the acoustic ones and a full and lustrous sound on violins. A rounded, full and intense sound on brasses like trumpets, trombones and horns. Then on woodwinds, it has a clear, rich, expressive and reedy sound on piccolos, flutes, clarinet and saxophones. As for percussive instruments, the tom-toms and field drums have a full, reverberant and warm sound, a hard and clattering sound on snare drums, and a resonant and rumbling sound on kettle drums. The piano sounds even and balanced as it has a bright and mellow tone with sufficient resonance.


HIGHS/TREBLE:

The treble quality that this device able to evince on my listening session, it has a smooth, evened and linear treble response with an unusually amount of sparkle and airy extension that most devices with Cirrus Logic DACs that I've quite familiar with, this device is quite a peculiar one.

Somehow it gives a more lustrous and full sound on cymbals and a short buzz and sizzle sound on hi-hats. A sweet and velvety sound on celestas and a bell-like sound on glockenspiels.


OVERALL TECHNICALITIES:

This device is able to project a fairly spacious soundscape with excellent height and depth that pairing it with warm-sounding sets gives that immersive and intimate feel but on IEMs and headphones with superb technical performance, it narrows a bit on the perceived distance. It still has an excellent layering on the placement of instruments and vocals with good separation on each element in a black sonic canvas.

In terms of resolution capabilities, this device is quite resolving on both macro-dynamics and micro-dynamics. It has a solid and firm texture on its dynamics as it has a proper compression while it has a good micro-detail retrieval as it is able to pick up on some subtleties like vocal ends, spatial reverberations and distinctive nuances of different instrument attacks.


PEER COMPARISONS:

TRUTHEAR SHIO

• This USB DAC/Amp dongle, like the DS2 is also equipped with Cirrus logic amp albeit a newer generation, CS43198. Its size is a bit larger compared to DS2 and yet it has similar weight, its surface was covered with PU leather and unlike the DS2, it has manual gain switch mode by pressing between the volume key buttons.
• On the tonal aspect, it also has a warmish-neutral sound profile like the DS2. Both have slamming and tactile bass response, a tad warmth on the midrange and a slight emphasis on upper-mids up to the presence part to give a little bit of energy with good airy extension and sparkling sound. Both sets have eerily very similar technical performance like moderately spacious sound/speaker stage projection, well-defined layering and separation and remarkably resolving on their own right. Although, I think that SHIO still has a more powerful output that can drive most of the stubborn and power-hungry headphones that demand more juice.

EPZ TP20 PRO

• Another dongle with Cirrus logic DAC with the same model IC. It has a broader frame compared to the DS2 as it is also carbon-fibre cover on the top and bottom panel. In additional features, it has a toggle switch and additional button key for pause and play function. And also, its stock cable is quite thicker and even a bit longer and of better quality.
• The TP20 PRO is also of a warmish-neutral side of tonality as it exhibits similar sound profile with DS2 albeit its treble response seems to less emphasis on upper-mids and presence part to give that smoother, a less energetic with just enough sparkle and a noticeable modest airy extension. Both devices have very similar performance of technical abilities as it is almost impossible to differentiate the differences between these devices. It also appears that both sets have similar power output delivery but on paper, DS2's power output has a maximum rating of 510mw at 32 ohms at its balanced output jack.

In summary, this DAC/Amp dongle is quite a performer and FOSI AUDIO continues to impress us on every release of their product. This DAC/Amp dongle shows that we can enjoy a high-fidelity sound quality in a compact and mobile form factor that it became more of a necessity for audio enthusiast like us given the removal of analogue features on most smartphone that deems “obsolete” for today's digital era according to these mobile phone companies (In which I'm still firm and adamant on disagreeing these notions). If you want a USB DAC/Amp dongle with some element of an analogue-ish tonal profile as it has a musical and fun factor that make it more engaging with competent technical capabilities, this might be the device that you are looking for.

FOSI AUDIO DS2 is now available in HIFIGO, you can check out the unaffiliated link below.


★★FOSI AUDIO DS2 - HIFIGO★★


Also, you can check out my previous review article of FOSI AUDIO products.


■ FOSI AUDIO MC101

■ FOSI AUDIO SK02




SPECIFICATIONS:



MY TESTING TRACKS: ( * = 16-bit FLAC, ** = 24-bit FLAC, *'* = MQA, '*' = DSD, *'= .WAV)

Alison Krauss -When You Say Nothing At All *
Jade Wiedlin - Blue Kiss**
Led Zeppelin - When The Levee Breaks **
Mountain - Mississippi Queen *
Queen - Killer Queen **
Guns N' Roses - Patience *'*
Eric Clapton - Tears in Heaven '*'
Sergio Mendes- Never Gonna Let You Go '*'
Pearl Jam - Daughter **
Roselia - Hidamari Rhodonite *
Assassin - Fight (To Stop The Tyranny)*
Celtic Frost- Visual Aggression *
New Order - Blue Monday *
The Corrs- What Can I do (unplugged version) *
Jimi Hendrix Experience - Voodoo Child *
The Madness- Buggy Trousers *
Metallica - Motorbreath **
Mariah Carey- Always Be My Baby *
Destiny's Child - Say My Name *
Malice Mizer- Au Revoir *
Mozart - Lacrimosa *
New York Philharmonic Orchestra - Dvorak- Symphony 9 " From the New World." *
Eva Cassidy - Fields of Gold (Sting cover)*
Michael Jackson - Give In To Me *
Exciter - Violence and Force *
Diana Krall - Stop This World **
Debbie Gibson - Foolish Beat *'*
The Sisters of Mercy – Lucretia My Reflection**
Suzanne Vega – Luka **
Lauren Christy – Steep *
Ottoman Mehter - Hucum Marsi *
Diana Damrau - Mozart: Die Zauberflöte*


P.S.

I am not affiliated to FOSI AUDIO nor receive monetary incentives and financial gains as they provide me a review unit for an exchange of factual and sincere feedback from yours truly.

Once again, I would like to send my gratitude to HIFIGO especially to Ms. Lvy Yan for providing this review unit. I truly appreciate their generosity and trust towards me and other reviewers.

Fosi Audio DS2 Dongle DAC Amp

For those who don't enjoy reading...

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DS2 (2024) Specifications & Product Details (Fosi Audio Website)

Fosi Audio DS2 2024 New Mini Audio USB DAC Headphone Amplifier​

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Unboxing (Photos)

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Build & Design

The first thing you'll notice when taking this thing out of the box is that it's incredibly light, at 15.5g without the cable and 20.2g with the cable.
It’s not exactly class-leading in that regard, but neither is it a heavyweight.

Hanging off the phone or stowed away in a pocket, the dongle hardly feels heavier than the rest of the cables and plugs it is connected to, which is vastly more reassuring than my previous experience with the DS1 which feels like a brick by comparison.

On the flip-side, I don’t get as much confidence from the thinner metal of the DS2 housing that it could survive more than a few drops or getting possibly bruised by a heavy water bottle in a backpack.

In any case, I think you simply have to decide what kind of dongle suits your needs best; the heavier and sturdier, or lighter and possibly more fragile.



Like the DS1, and many other dongles it has two different coloured sockets, which at the very least can be considered an easy visual way to distinguish between the 3.5mm and the balanced 4.4mm.

Once again I’m more than happy to see the continued implementation of a detachable USB-C cable.
Since I’ve been using these twisted rope-type cables for a while now, I’m getting more convinced that they are a long term solution, as they have a bit more stretch and compression than other cables, and are practically immune to twisting.



The provided USB type A to C adapter still has the same finish as the cable connectors and are are also finished in the same colour as the DS2 unit itself, making them an obvious visual pairing.

The volume buttons remain unchanged using the same old symmetrical design, so in the pocket it is not obvious which button is volume up and which is down.
When used with a computer or laptop, with the USB cable leading away from you, the volume buttons are in the intuitive positions.

Overall the build is satisfactory. After a couple of weeks I have noticed a few small marks starting to appear on the surface of the metal, so it’s not impervious to wear and tear.

I’m a little disappointed to see that the buttons are still the same.
I would have liked to see an asymmetrical button layout implemented, with one button being longer or larger than the other. Over time one could then use the volume controls automatically without looking at the unit.

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Functionality

The DS2 has a few different LED colours.

The Blue LED simply tells you when it’s connecting to a device like a phone or laptop. Normally you will only see blue for a moment.
Then you’ve got red for PCM playback up to a sample rate of 48KHz, green up to 96KHz and orange up to 384KHz



Other than that there isn’t much to it.
This dongle appears to be made for ultimate simplicity and user-friendliness.

The downside to this for some may be that there is no volume indicator.
Another issue is that holding down either of the volume buttons does not raise or lower the volume quickly.

You have to press the volume button manually many times to reach either extreme.
This won’t be an issue for most users who control their system volume through the operating or their media player directly, or their mobile phone system volume.

Also there is no companion app, so for some this will be a negative point, while others will prefer the plug and play simplicity.

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Measurements and Sound

Overall with my ears I can’t detect any significant change in the sound quality or tone from the Fosi Audio DS1, SK02 or my other amps.
In my previous DS1 review I already determined that most of my amplifiers and dongle had no obvious measurable effect on a Sennheiser HD650 seated in the same position.

However in this instance, the DS2 has actually made a small and unexpected difference.



While my other amps all produce graphs that almost perfectly overlay on top of each other, the DS2 has some minor deviations between 1000 and 6000hz.

The only significant change is a 2dB scoop between 2 and 3KHz.
Practically with some headphones this can actually reduce glare from instruments and vocals that sound too far forward or prominent and improve the sense of soundstage.

It’s not a bold tuning by any means, but neither is it objectively bad or distasteful.
On the contrary, to the most golden of ears, this may be a welcome change.

Personally, I can barely hear such a minor difference, so for me that’s a plus in it’s own way, since I prefer my headphones or EQ settings to do the work, but at most it may give the slightest feather touch more warmth to the sound.

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Comparisons

The main comparison I want to make is between this and the DS1.
Going back and forth between the DS1 with it’s ESS ES9038Q2M chips and the DS2 with it’s Cirrus Logic CS43131 DAC chips, I really wanted to hear a glaring difference.

I’ve got plenty of experience listening to music from various sources with ESS and Burson chips so I happy to report that there are no obvious differences from the Cirrus Logic chips.

For me DACs continue to be the least interesting aspect in the audio chain; which is EXACTLY how I would want things to remain.
It’s already confusing enough having hundreds or even thousands of different flavours of headphone and IEM, which is compounded by the subtleties of amplifier design.



I’m happy to say that the absence of additive flavourings was consistent throughout various headphones, flathead earbuds and IEMs.
The DS2 had no trouble driving either extremely sensitive IEMs without adding even the slightest hint of background noise, nor driving highly demanding full sized planar headphones.

The objective result of using these Cirrus Logic DAC chips specifically in the DS2 actually have further benefits.

According to the marketing on Fosi’s website the DS2 uses “Low-power Technology”, and from the time I’ve used it on my phone, I think might actually consume less power than the DS1 so unlike the DS1, the DS2 also never got warm to the touch.

Automatically you might think “OK, so it uses less power, so it must be a weaker amp” and you’d be wrong.
The new 2024 model with the Cirrus Logic chips is over twice as powerful as the previous DS2 model and the DS1, and can reach ear-splitting volumes out of it’s regular 3.5mm output.

The balanced output is more than capable of adequately driving some of the more demanding headphones around today.

Whether it ends up consuming more power the more demanding headphones and higher volume you use is still up for debate as I have not tested this, but I think it would be more than fair to assume that would be the case.



Conclusions

I’m not sure what Fosi Audio is doing here because I feel like they’re undercutting themselves with the new DS2.
It’s lighter, more powerful, more user-friendly than the DS1, and cheaper.

I think anyone looking for their first dongle DAC amp should take a very serious look at the 2024 DS2.

It’s balanced output power of 510mW into 32 ohm is quite frankly an insane achievement for such a small dongle, easily rivalling the power of many entry and mid level desktop sized headphone amps.


I’ve noticed a running theme starting to occur with Fosi Audio.
POWER
All their recent products have been aimed at bringing as much clean, usable power to the user as possible for as little money; and this is by far no exception.

The DS2 obviously won’t give higher end desktop amps a run for their money; it doesn’t offer quite the same musical performance as my NFB11.28 or SK01, but for the size and weight, it’s actually kinda nuts.

Disclaimer:​

Good morning, readers! Today, we are going to test the new Fosi DS2. The dongle has undergone a hardware review and now has a certain interest, especially in the entry-level range. As usual, I thank Hifigo for the review unit.


The Fosi DS2 features two CS43131 chips. The market is now full of dongles that use this chip and the choice is increasingly complex. However, the new DS2 has price and power as its strong points.


The review, as always, will be completely unbiased and uninfluenced.


I would like to remind you that I am just a person who enjoys trying out new items and listening to a lot of music; I am not an expert.


My opinions are obviously subjective.

Tech Specs:​

• Dual CS43131
• Sampling Rate: 32-bit, 384khz / DSD256
• THD+N: 0.0001%,
• Noise: <1.6UV.
• Frequency response: 20Hz-20kHz (±0.5dB)
• S/N: ≥130 dB
• Power : SE: 130mw /32Ω, BAL: 510mw /32Ω
• Hi-Res certification
• Independent volume

Packaging:​

The packaging is very simple, I would even say a little oversized, half the box was enough.


Fortunately, inside, we find the following accessories:

• Type C to Type C cable
• USB A adapter (always much appreciated)
• Manual

In terms of first equipment, I think it’s more than fair. The Type C cable reminds me of some cables I’ve already seen, very flexible.

Build quality/First impressions:​

I’ll start by saying that I didn’t own the old DS2 but judging from what I’ve seen, the shell is identical. They have kept the same design with an aluminum shell, which is very light but resistant. Personally, I really like the gunmetal-like color; aesthetically, it is very minimal. On the front, we find the LED and the “Fosi Audio DS2” labeling, and on the back, we simply find the Hi-Res sticker.


On one side, we have the volume buttons and nothing else. Personally, I would have liked to find something written on the shell so as to immediately identify that it was the new model. The gain switch is missing; honestly, I would have put it there. It’s not essential but let’s say that if you have particularly sensitive IEMs, in some cases you might need it. But fortunately, it still has independent volume and allows precise volume adjustment.

Power:​

The Fosi DS2 has decidedly generous outputs; the declared values are both at 32 ohms, so for headphones with lower ohms, you will have considerable power available.


To give you an idea of the DS2 power, with the 28-ohm Kefine Delci and the volume set to maximum, my iMac only requires three volume bars out of sixteen. Getting to half the volume is extremely difficult. You won’t have any kind of problem with any IEM that comes out with SE cable.

Macro Outputs
While the 4.4mm side provides even more power, switching to the Hidizs MP145 requires only 5 volume bars out of 16.


The thing that surprises me is that despite the decidedly low price, it is one of the most powerful CS43131 dongles currently on the market. By now, the entry-level products have reached decidedly very high quality. With a product like this, you can easily use planar headphones without problems.

The lack of a gain switch is made up for by an independent volume that combines with the volume of the device to which it is connected, giving you many more adjustment possibilities.


During the test with my iMac, I discovered a strange peculiarity: when I stop and restart a song, the volume gradually increases (which I think is a fantastic feature); however, I have noticed that the volume sometimes comes from one channel rather than the other. The operation is bizarre, and I am not sure if it is a firmware bug or not, but it seemed appropriate to inform you. There were no issues while changing tracks.

Sound Signature:​

The Fosi DS2 is slightly atypical for a Cirrus Logic dongle. In terms of sound signature, it is more similar to the new CS43198, although in terms of definition and refinement of the sound, we are more on par with the newest CS43131 on the market. The bass is slightly smoother; it follows the bright line, giving it the right balance with some aspects of the Fosi SK02. It has a decidedly brighter sound than other Cirrus Logics, with a good soundstage and amount of detail. It has some resemblance to the iBasso DC04Pro; both are practically colorless and very flat, although in my opinion the DC04Pro has a very slight difference (in its favour) more in terms of soundstage and refinement of details.


The New Fosi DS2 costs practically 60 USD and has a very high output power that you can’t complain about and the differences in terms of details can only be noticed by those who have many other products to compare. An entry-level user who picks up such a dongle can only smile from the first listen to the last. Basically, it is a very natural-sounding dongle, and I feel it has a very flat sound compared to many others. You might like it for this feature. There aren’t many DACs without coloration.

Fast Comparison:​

If you want other comparisons just ask and I will answer you.


vs EPZ TP20 Pro


The EPZ TP20 Pro is an excellent dongle; it sounds extremely good, they have improved the shell, it has the gain switch but otherwise it has no other features. We can say that it is very similar to many others in terms of configuration. It sounds great but it comes at a higher price than the others.

vs Hidizs S9 PRO Plus​

With Hidizs S9 Pro Plus, if you like warmer and slightly more present instruments and voices, the Hidizs sound signature doesn’t miss a beat. It has currently dropped in price so its purchase is very close to the price of the Cirrus Logic dongles, which, as we know, are the cheapest. Personally, I like it a lot but if you have some planar to experiment with it, the Fosi DS2 has more power in reserve.


vs Moondrop Dawn Pro


The Dawn Pro was the CS dongle that dominated the others. Very low price, working app with some settings, compact shell but with some defects. But for 50 USD, it’s honestly one of the best entry-level ones yet. They are slightly different; the Moondrop has a slightly warmer sound coloration and a slightly nicer design (personal) but sometimes the QC strikes. Honestly, I would currently opt for the Fosi DS2, which is slightly more powerful and therefore should be enough for several IEMs and headphones. The app isn’t that essential.


vs FiiO KA11

FiiO Ka11
It may seem crazy to you, but with a small dongle like this, many of us will be completely satisfied. With its unique outputs, it has few competitors in terms of SE output. Most of us use headphones with the classic 3.5mm jack, so the FiiO KA11 is all you need. The app works reasonably well, and there are firmware updates available. With its features and, above all, thanks to its slightly warmer sound, it has become one of my favorite dongles for everyday use. Especially when I’m traveling, it’s the most compact solution possible.

Who do I recommend this DAC to?​

The Fosi DS2 competes with the other dongles mentioned above. I think for the price, this one slightly beats the Moondrop Dawn Pro in terms of build quality and versatility. Moondrop has an app and you have the ability to manage some dongle stuff but at the same time, the quality of the dongle is slightly lower than the Fosi DS2.


In direct comparison, the choice depends on your preferences; they both sound very good for entry level and personally, I would choose the new Fosi DS2 as the versatility is greater. As regards possible distortions, in my opinion, they wanted to keep a very high gain to have a greater volume, even on devices with software and hardware limitations. This means that the volume setting on the dongle should be kept lower. I doubt that any of you will reach such high volume levels.


Regarding the soundstage, I was influenced by the last month, in which I only used the FiiO KA17. Initially, I wasn’t particularly surprised, as I was on higher-performing models but after carrying out a comparison with the others, I noticed that it was almost on the same level. The Fosi DS2 performs very well, especially for its price. Consider that the similarity with the DC04Pro is truly remarkable, unlike the fact that iBasso has the app to manage some features of its dongle.

Where to buy?​

Fosi Audio DS2 Dual CS43131 Portable Dongle DAC Headphone AMP

Introduction​

Fosi is well known in Chi-Fi and has released some DAC/AMPs that were praised by many in the community. The DS2 is their latest dongle featuring both unbalanced and balanced outputs and comes in a very small format with USB Type-C connection.

Disclaimer: the Fosi DS2 was sent to me by HiFiGO free of charge in order to write an honest review. This review represents my personal opinion and it is by no means a promotional or paid content.
At the time of the review, the Fosi DS2 was on sale for around 59$ at HiFiGO.

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As an important note, it seems like Fosi Audio has made a revision of this product since some have received the variant with the ESS9018K2M and others (like me) have received the variant with the CS43131, so be aware of this when looking at the various reviews as some opinions may vary substantially.

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Technical Specifications​

• Size → 53mm * 19mm * 12mm
• DAC Chip → Cirrus Logic CS43131 x 2
• Compatibility → PCM 32bit 384kHz, DSD256 (NO MQA)
• Output type → single ended 3.5mm jack, balanced 4.4mm jack
• Frequency Response → 20Hz-20kHz (±0.5dB)
• THD → 0.0001%
• SNR → 130dB
• Crosstalk → 117 dB
• Output Power → SE: 130mW@32ohm - BAL: 510mW@32ohm
• Recommended headphone impedance → 16Ω-300Ω
• Supported systems → Android, Windows, Mac OS, iOS (if you have older iPhones, though, you’ll have to buy a Type-C to Lightning adapter separately)
• Net weight → 15g

Packaging​

The box is very small, it has a very simple design and contains:

• The Fosi DS2
• A Type-C to Type-C cable
• A Type-C to USB-A adapter
• User manual and warranty card

Design, Build Quality and Buttons​

The Fosi DS2 has minimal design and it’s built like a tank. It’s also very lightweight and very small, and one can easily carry it in a small case with a pair of IEMs.



There are two dedicated buttons for the volume control, which are independent from the source volume (increasing the volume on the dongle doesn’t affect the source volume, so I just increase the source volume 100% and then adjust the volume directly on the dongle).
Unfortunately, even though someone reported that pressing both buttons together switched to the high gain mode, this is not the case on my DS2: this is probably due to the above mentioned recent revision of the product.

Performance​

Power consumption and temperature
The Fosi DS2 packs a lot of power: my Hifiman HE400 SE reach pretty high volumes and I can’t wear them if I max the volume or I’d risk becoming deaf very fast. For sure it's not the best dongle to pair with a neutral bright set and in fact I don't enjoy the HE400 SE a lot with the DS2.
It’s also an efficient dongle since it doesn’t consume a lot of power and doesn’t become very hot after a few minutes of listening. Listening to some high-res FLAC files on my Galaxy S23 Ultra with HiBy Music consumed 4% of battery after half an hour and the dongle DAC was still far from being warm to the touch, which is an overall good result in my opinion. Other dongles with higher operating temperatures would have consumed more power, and this is also thanks to the CS43131 being a very efficient solution.

Sound
The DS2 is transparent with a slightly bright tinge. It’s very resolving, detailed and analytical, and pairs well with warmer sets due to its dry nature. The soundstage isn’t the best out there, and in fact the sound is rather intimate (and makes warm IEMs even more intimate). Also, there isn’t any background noise or hiss with sensitive IEMs, and the overall response is not smoothened nor softened in any way.

I want to report, in addition, that if you pause and wait a few seconds, then when pressing play again the dongle will smoothen the volume instead of start playing at full volume in order to prevent hearing issues, which is good news. Unfortunately, though, the sound doesn't stop when the earphones are disconnected.

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Some comparisons:​

Fosi DS2 vs Truthear SHIO
The SHIO sounds a bit warmer and more natural, and the portrayed soundstage is slightly more spacious. It is also more powerful from my testing and has two gain settings to choose from. The SHIO is slightly more capable when it comes to the maximum sampling rate, going up to PCM 44.1 kHz - 768 kHz while the DS2 tops up at 384 kHz (more of a number thing, since it’s very hard to notice differences once these sampling rates are reached), even though both support up to DSD256. Power consumption is very similar and temperatures are not an issue on both (the SHIO is also covered by a very cheap pleather skin so it feels a bit less warm due to the fact that there’s another layer).
The overall build quality is superior on the DS2 whereas the SHIO looks and feels a bit cheaper (despite being slightly more powerful). Both have volume controls, which is good news.

Fosi DS2 vs Hidizs XO
The Hidizs XO is warmer, and slightly smoother in the upper end with a tad more low-end body. The DS2 is a bit brighter instead and more transparent, sounding slightly drier than Hidizs’ dongle.
In terms of power and efficiency, the DS2 can reach higher volumes and it does that without becoming very warm/hot after some minutes of listening, a thing that happens instead on the Hidizs XO and that leads to more power consumption than the Fosi DS2.
Both are built very well, they are very lightweight and portable, both feel solid in the hands and both sport an added 4.4mm jack port for the balanced output, along with the unbalanced 3.5mm port. The Hidizs XO has RGB lighting but doesn’t have any volume control buttons, and the sound filters are basically identical in terms of sound. Another important difference is the fact that the XO sports a 2.5mm balanced port, whereas the Fosi DS2 features a more common and safe 4.4mm output (2.5mm outputs aren’t very appreciated because 4.4mm connectors are generally less delicate on the long run).
The XO is not a bad dongle but the Fosi DS2 is a product with an overall higher value for money, even though they sound slightly different in terms of sound approach..

Fosi DS2 vs Type-C Apple Dongle
Easy one: the DS2 is more resolving, more powerful, more versatile also thanks to the double output (balanced + unbalanced) but it’s also much more expensive. The Apple Dongle can be found for around 6$-7$ on average and it’s a very transparent and versatile device if you use it on your PC, on an unlocked android phone or with a few apps (due to the fact that it has a very limited output if not under specific/optimal conditions). One thing to say is that the Apple Dongle also works with TRRS connectors, also transmitting microphone input, a thing that isn’t possible on the Fosi DS2 due to it having audio outputs only.

Final Thoughts​

The Fosi DS2 is an excellent portable dongle DAC/AMP: it has lots of power, it’s very efficient and the price is right, which is not something to take for granted. To be honest, the only thing that bothers me is the lack of a proper gain switch, but since the dongle volume is independent from the source volume, it’s something that I don’t consider as a dealbreaker.

DISCLAIMER

I would like to thank HIFIGO for providing this unit.

The Fosi Audio DS2 Cirrus 2024 version can be gotten here: https://hifigo.com/products/fosi-audio-ds2 (no affiliate links).



Take note that there was an older Fosi Audio DS2 utilizing ESS chips. The dongle we are talking about today is a newer variant for 2024, which packs dual CS43131 chips.


SPECIFICATIONS/COMPATIBILITY

DAC Chip: Dual CS43131 Cirrus Logic chips
Output ports: 3.5 mm single-ended and 4.4 mm balanced
Output Power: SE: 128 mW (@32 Ω), BAL: 510 mW (@32 Ω)
Playback: PCM up to 32 bit/384 kHz; DSD 64/128/256
Dynamic range: 130 dB
THD+N: 0.0001%
Noise: <1.6 UV.
Frequency response: 20 Hz - 20 kHz
S/N: ≥130 dB
Tested at: $59.99 USD


This is a plug-and-play dongle, and as a Windows 10 user, I did not require any additional drivers to be installed. It was easily recognized on various Windows and Android devices, but I cannot vouch for its compatibility with Apple products, as I'm not a user of their gear.

This dongle has no app or UAC 1.0 mode for gaming.


ACCESSORIES

Other than the dongle, the packaging comes with:
- USB-C to USB-C cable
- USB-C to USB-A adapter



Truth be told, it is a decent provision of accessories, perhaps other than the omission of a Lightning adapter for our Apple friends.

The provided USB-C cable is on the thinner side, but is pretty well braided.


DESIGN/FUNCTION



The DS2 Cirrus 2024 dongle is furnished from matte grey metal, and comes in a well-built rectangular design. It is very tiny, and easily fits in a pocket or small bag.

There is an LED light on the top, which changes colours based on the file format used:

• PCM < 48 kHz: red
• PCM 48 - 96 kHz: green
• PCM 96 - 384 kHz: yellow
• DSD 64/128/256: blue

This dongle has no screen, nor any settings menu to explore. Neither has it any gain or DAC filter options, so it is pretty no frills.

One side has the 3.5 mm (single-ended) and 4.4 mm (balanced) ports, with the latter reinforced by gold-plating.




The opposite side has a USB-C port for data and power feed.




On the lateral aspect, we have independent volume controls with very finely tuned steps - this is much appreciated as some higher-end dongles like the Questyle M15 for example, do not have this implemented.


INTERNALS

This DAC/AMP's engine are dual CS43131 chips. It allows playback of PCM up to 32bit/384kHz and DSD up to DSD256.


SOUND/PERFORMANCE

I tested the DS2 Cirrus 2024 with only Android phones and Windows laptops and PCs. Once again, I'm not an Apple user, so I can't confirm its performance with Apple ecosystem sources.

On phones, I used the HiBy Music Player, with USB bit perfect OTG activated on a Samsung S22.




Tonally, the DS2 Cirrus 2024 is neutral and achromatic. This makes it a perfect option for purists who want only the transducer to do the colouring. It is very clean sounding, and gear that you are familiar with should sound exactly the same on pairing it here. End-to-end extension is good with no roll-off.

Technicalities are nicely done for a $50ish dongle. We hear an expansive soundstage in depth, height and width. Music is projected beyond the ears, and this is one of the better dongles in soundstage at sub-$100. Micro-details are captured well. Imaging is quite pinpoint, and one can hear projected instruments and vocals within the headspace with relative ease.

This dongle has a single-ended (3.5 mm) and balanced (4.4 mm) port. Fosi advertises 128 mW (@32 Ω) for the single-ended and 510 mW (@32 Ω) for the balanced port respectively (with a reported THD+N: 0.0001%). Unfortunately, the DS2 Cirrus 2024 has no gain options.

These purported power specs are actually quite impressive for a $50ish dongle, as the next step up would be the pricier Fiio KA13, which juices out 550 mW on its balanced desktop mode. Well, the proof lies in the pudding, and I put this DAC/AMP through my gauntlet of hardest to drive gear:
1) Final Audio E5000 (low sensitivity at 93dB/mW)
2) Sennheiser HD650 (high impedance at 300ohm)
3) Yinman 600 ohm (600 ohm impedance and 87db/mW sensitivity)

On balanced output, the E5000 was surprisingly well-driven, with a textured bass with good control of the bass. The HD650 had adequate dynamics, though the soundstage sounded a wee bit compressed.

The final boss, the Yinman 600 ohm - with a ridiculously high impedance and low sensitivity - was understandably underpowered. It is not a matter of volume, but the bass was somewhat bloated with lack of texturing, though dynamics and staging were adequate. It is no shame though, most dongles and DAPs can't drive this behemoth well, and it usually requires desktop grade sources to suitably drive it.

I did note a bit of distortion on driving these tough customers (especially the Yinmans), so perhaps the THD may not be as clean as marketed.

While we have no output impedance (OI) specifications provided by the company, to my ears, the OI should be relatively low, as low impedance gear paired with it didn't sound warped in the frequency response.

This device has no hiss even with highly sensitive IEMs. There is no "pop" sound on disconnecting gear, which is a sign of good noise floor implementation. The DS2 Cirrus 2024 gets slightly warm during usage (but not hot).



COMPARISONS

Simgot DEW4X

The DEW4X's engine are dual C43198 cirrus chips, and it has a warm-neutral tonality. Thus, it sounds thicker in note weight than the DS2 Cirrus 2024, and has a more rounded and laid-back profile.

Both dongles have independent volume controls with finely tuned steps, but the DEW4X has gain functions, with a UAC 1.0 gaming mode, so the versatility is a bit better.

On high gain via the 4.4 mm port, the DEW4X is rated for 150 mW output, which is paltry compared to the DS2 Cirrus 2024. Thus the DEW4X's anemic driving ability cannot juice more demanding gear.

In terms of technicalities, the DEW4X is weaker in soundstage, micro-detailing and imaging.


Fiio KA13

The KA13 is a neutral bright dongle that utilizes dual CS43131 chips.

The KA13 is better accessorized - it even has an Apple adapter included - with a Fiio control app for additional areas to explore. The KA13 likewise has well-implemented independent volume controls.

The KA13 on 4.4 mm desktop mode pumps out 550 mW output (THD+N balanced＜0.0005% (32 Ω)), which on paper is just slightly better than the advertised specs on the DS2 Cirrus 2024. However, at high loads, the KA13 doesn't distort so easily when driving difficult transducers - in contrast to the DS2 Cirrus 2024 - so I feel the former has a more controlled power delivery. The KA13 gets warmer during usage, and has a greater battery drain, which ties in with the great power outlay.

In technicalities, these 2 are neck-and-neck. The KA13 has better micro-detailing and imaging, but the DS2 Cirrus 2024 has a more expansive stage. The KA13 is about $20 more expensive though.


CONCLUSIONS



The Fosi Audio DS2 Cirrus 2024 is a solid dongle to consider in the competitive $50ish market. Its forte is in soundstaging, with an expansive soundscape heard beyond the ears, something that belies its relatively low price point - it actually comfortably beats most other $50ish competitors in this department.

This dongle is neutral and uncoloured, so it lets the connected transducer do the talking. Accessories, build, and portability are great for the asking price. It doesn't get hot during usage, with no hiss or "popping" too.

While the power specs on paper look audacious, on actual field testing, the DS2 Cirrus 2024 does run into instances of distortion when required to pump harder to drive gear. No doubt it can still drive relatively demanding gear, but the power isn't as clean, and as the adage goes, "power is nothing without control". This dongle also has some lack of features, such as no app, PEQ, DAC filters or even gain settings.

In the big scheme of things, the Fosi Audio DS2 Cirrus 2024 variant is a no frills dongle. It should be considered in the conversation for something with quite a lot of juice, yet retaining neutrality with a good sprinkling of technicalities, especially in soundstage.

The updated version of the Fosi Audio DS2 Dongle DAC is equipped with Dual Cirrus Logic CS43131 DAC chips, this compact device delivers powerful performance with single-ended power output of 128mW (32ohms) and balanced output of 510mW (32ohms). Its frequency response of 20Hz-20kHz with a deviation of only +/- 0.5dB ensures accurate sound reproduction across the audible spectrum. Supporting PCM up to 32bit/384kHz and DSD 64/128/256, the DS2 provides versatility for various audio formats.

With a dynamic range of 130dB and an incredibly low THD+N of 0.0002%, the DS2 delivers pristine audio reproduction with exceptional clarity and detail, making it suitable for critical listening sessions.

Despite its compact size, the DS2 offers robust power output, particularly in balanced mode, providing ample drive even on some planar headphones and earphones.

The DS2 has a neutral to bright sound signature, characterized by clarity and precision, it has a wide airy sound stage, with good mid bass focus its fast punchy well defined bass with clear emphasized mids, natural sounding vocals and energetic and well extended treble with just the right amount of sparkle to give more detail and clarity, stellar instrument separation adds to a more holographic sound.



Compared to the Shanling UA4 Dongle DAC, the Fosi Audio DS2 offers several advantages, particularly in terms of power output and technical specifications. While both devices provide high-resolution audio support and compact form factors, the shanling ua4 offers a more complete feature rich dongle with a status screen, app support, filters and gain switch to name a few but the DS2 stands out with its simple compact elegant design with just a volume buttons on the side and a small rgb light to indicated track file type and a higher power output in both single-ended and balanced modes, and lower THD+N. Additionally, the DS2's neutral to bright sound signature may appeal to users seeking precise and detailed audio reproduction, whereas the UA4 may offer a different sonic character depending on individual preferences. Ultimately, the choice between the two devices may come down to specific audio requirements, budget considerations, features and personal sound preferences.



While the DS2 is a very good dac like any other dongle dacs its not without fault, i noticed when pushing the ds2 on balance 4.4 to almost max volume (painfully loud) using my Hifiman he400se planar headphones and ARTTI T10 planar iem there is a very noticable distortion on low and mid frequencies. i do believe the proclaimed output of 510mw on balance is accurate but its pushing the ds2 to its limits and resulting to a very noticable distortion.

I also noticed when using the DS2 on Samsung Galaxy tab A8 tablet, Samsung S23 Ultra mobile phone the sound cuts off and restarts every 10-20 seconds i tried tweaking usb settings on my tablet and the UAPP, Hiby and Tidal app, changed cables etc.. still the sound cuts off making the DS2 useless but it works perfectly on my old iphone 7 plus, ipad mini, iphone Xs Max and my older Samsung Galaxy tab A7. Hoping that Fosi Audio will have a fast fix for this compatability issue.

The DS2 is a very good sounding powerful dac, the compact elegant simple design, with stellar detail and clarity compared to dongle twice its price. it truly performs above its price range BUT with the current compatability issue in some android devices it is a total deal breaker for me. i would advice android users to wait until they fix this problem and for IOS users to go get one i have tested it with old and new models of iphone and ipads and i can confirm that there no issues with sound cutting off. this is really a good sounding solidly built dongle dac that out performs some that is above its price point.

I will update my post once Fosi Audio releases a fix for the Android compatibility issue.