Fosi Audio DS2 (2024 Cirrus Version)

Fosi Audio DS2: High-Power Portability in a Compact Package​

The Fosi Audio DS2 is a portable USB dongle DAC/amp that combines clean design with impressive performance.

Note: I would like to thank Fosi Audio for sending me DS2 not for this review but as a gift for assisting them with a research survey. But if you are interested in more information about the DS2 check it the details: here
But let’s see what you get with the DS2:

Unboxing Experience and Box Contents​

The DS2 comes in straightforward packaging that reflects its minimalist design philosophy.


Open the box:



Inside the box, you’ll find:



Finally, here is everything you get in the box:

• Fosi Audio DS2 dongle
• USB-C to USB-C cable
• USB-C to USB-A adapter
• User manual and warranty card

The inclusion of a USB-A adapter is a thoughtful touch, ensuring compatibility with a wider range of devices.

Design and Build Quality​

The DS2 boasts an understated design, with a robust aluminum chassis that feels premium and durable. The clean, functional aesthetic makes it a perfect match for any setup.


At just under 20g, it’s lightweight and portable, ideal for on-the-go audiophiles:



Both the 3.5mm and 4.4mm outputs are well-constructed, providing a secure connection for headphones. The DS2 features a small status LED that changes color to indicate sample rate and playback type (PCM or DSD), adding a functional touch without cluttering the design.

Key Features​

Dual DAC Architecture for Superior Audio Quality​

The DS2 is powered by dual CS43131 DAC chips, delivering excellent dynamic range and low distortion. This architecture ensures precise channel separation and transparency, making it an excellent choice for audiophiles who prioritize uncolored, accurate sound reproduction.

4.4mm Balanced Output for Enhanced Power​

With its balanced 4.4mm output, the DS2 provides up to 510mW of power at 32Ω, capable of driving most headphones with ease. The single-ended 3.5mm output is no slouch either, offering a respectable 130mW at 32Ω.

Cross-Platform Compatibility​

The DS2 supports plug-and-play functionality across all major platforms, including Windows, macOS, Android, and iOS ( with an appropriate adapter for Lightning devices). It also supports high-resolution formats up to PCM 384kHz and DSD256, ensuring you can enjoy your music in its highest fidelity.

Sound Impressions​

The Fosi Audio DS2 delivers a neutral, transparent sound signature with no noticeable coloration. This makes it an excellent choice for purists who value accurate reproduction.

Bass​

The bass is tight, controlled, and well-extended. Tracks like “Another One Bites the Dust” by Queen showcase the DS2’s ability to deliver punchy, precise low frequencies without overpowering the rest of the spectrum.

Midrange​

The midrange is detailed and natural, with a pleasing sense of clarity and warmth. Vocals and instruments are rendered with excellent separation, making tracks like “Hello” by Adele an immersive experience.

Treble​

The treble is smooth and detailed, avoiding harshness or sibilance. High-frequency details in tracks like “Take Five” by The Dave Brubeck Quartet are presented with air and sparkle, enhancing the overall listening experience.

Practical Measurements and Comparisons​

Why I am calling this a ‘practical measurement’ section?

DAC are like transparent windows​

You will often see reviews on head-fi (and other websites) talking about the subjective differences between different headphone DAC amps, one having a better bass response or another focusing on the midrange while a third might give you a more detailed treble and this was certainly the case in this market as recent as 3 years ago. And especially the case at both the cheaper end of the market (as the technology was not as matured) but it can also for the very high end where manufacturers want to distinguish their devices with unique sound signature.

But in my opinion, DAC and Amplifiers should not (by design) change the sound signature, though obviously some implementations are better than others and some implementations (like Tube amps) will deliberately ‘colour’ your sound (like a stained-glass window). Older cheaper designs would also affect the extremes of your sound (the sub-bass) or poor filter implementations (near 20,000Hz) - maybe like glass that has ‘blurry’ or ‘frosted’ edges but then crystal clear in the middle.

I believe the best DAC and Amplifiers should be perfectly transparent and let your music be ‘seen’ perfectly clear by your headphones and IEMS (and Speakers), unless you choose some EQ to your preference.

Measurements of an old DAC compared to a modern one​

Few manufacturers would publish their measurements but as an example I did find during my recent review of the FiiO KA15 some earlier measurements of the FiiO K3, for comparison and the difference I think perfectly illustrate the point that the industry has moved on. Below is the FiiO DAC K3 from 2019 compared to the latest KA15:

While from 20-20,000Hz the K3 was a mostly flat it does roll off while a modern DAC will (should) be transparently ‘flat’.

Selection of a Headphone for ‘Practical Measurement’​

Rather than compare DAC Amp SINAD charts, I thought for this review it might be more fun to see how well does this DAC Amp (and a few other portable DAC amps) perform when driving a real headphone to loud ‘90+ dbSPL’ volumes and then measure the output from that the headphone to see if it is still transparent. This is to remove most of that typical uncertainty that I read when people just read DAC or Amplifier measurements (i.e. ‘but how will it perform with my XXXX headphone’ ).

So over at AudioScienceReview Amir has been putting together an interesting graph of how hard it is to drive any headphone that he has measured, and it is becoming a very extensive and interesting list covering most of the ’normal’ headphones (and some very expensive ‘high end’ headphones). Here is the latest version of that chart:



For those interested here is the source of this version of the list is from his latest: DCA Noire X review

So I thought I should use a headphone from the bottom end of this chart as a good ’test’ of these DACs, so I picked the Hifiman Sundara (as I am about to publish a review of that headphone). So here is that section of the list zoomed:



As you can hopefully see I thought the Hifiman Sundara was a good ‘challenging’ part of this chart. So lets see how the Macaron does. But first I thought I should measure the Sundara with various Headphone DACs to compare if there is any ’tonality’ differences:

Hifiman Sundara FR with various DACs​

So in this test I measured the Sundara using my KB501X softear pinna and a 711 clone coupler and I decided to ‘volume level’ the output measured (as close as I could) with the various DAC Amps:



As you can hopefully see each one of the devices used produced the same result (i.e. they were all transparent at 90+ dbSPL). I even started using my Macbook Pro own headphone jack, then the Apple usb-c, and then I followed up with both the single ended and then the balanced output of various dongles.

Here a photo of the dongles (including the Macaron) that I used in this measurement (though I didn’t measure the Qudelik 4K and the FiiO KA17 in this particular comparison):



So in this photo the ones I used are Fosi Audio DS2, FiiO KA15, iBasso Jr Macaron, Kiwiears Allegro and the Kiwiears Allegro Mini on the right-hand side of this photo.

So the point of this is each of these devices can drive a ‘hard to drive’ headphone but what ‘headroom’ do they leave for that track that has high dynamic range or for applying EQ filters (often needing an extra 10dbSPL).

To capture this I used my Macbook Pro to ‘record’ what volume was needed to drive each device to this ‘volume matched’ level (except with the Macaron I had to use Macaron own volume buttons and I did not enable the high gain or turbo modes within the iBasso UAC Companion application as this was the default).

I believe you should always have some headroom when driving headphones so having more volume available, the better but which of these devices has ’enough’ for your use-case (on this relatively hard to drive headphone), so low volume is better:

I think it’s pretty impressive that all these devices could drive the Sundara to a pretty loud 90+ dbSPL, but what does each cost:

So the KA15 is considerable more expensive but does have a little more power, a screen and PEQ capabilities via a companion application.

Since, the Allegro Mini is really just slightly more powerful than the Apple USB-C dongle it benefits are the conveniences of having both a 3.5mm and 4.4mm and its super compact size.

While the iBasso Jr Macaron is the cheapest of the “dual CS43131” models, it also has a ‘companion’ application and if you are an Android user and for Android users it probably offers the best overall offering. But the Fosi Audio DS2 is a fantastic looking device that also provide excellent price / performance ratio and is my favourite for iPhone users.

Given that all these devices are “transparent” with a relatively ‘hard to drive’ headphone at 90+ dbSPL we are at a golden age for ‘pragmatically’ price portable audio devices.

Distortion Measurements​

One thing I did not measure of these DAC’s was the SINAD and distortion but recently Amir over at AudioScienceReview reviewed the DS2 and found it an exceptional DAC from a measurement perspective.

While SINAD doesn’t really tell you anything other than how well it is internall built (assuming the SINAD is over about 80) it is an impressive result and it currently top of the SINAD charts for portable DACs:

And it worth showing the multi-tone results:

Rating​

The Fosi Audio DS2 delivers a compelling combination of power, transparency, and compatibility with all major platforms (Windows, macOS, Android, and iOS). Its dual outputs (3.5mm single-ended and 4.4mm balanced) ensure it can drive everything from sensitive IEMs to more demanding headphones with ease.

The Fosi Audio DS2 earns a 5-star pragmatic rating for its clean design, platform compatibility, and exceptional power output. At its price point, it represents outstanding value for those seeking a transparent, powerful USB dongle DAC/amp.

Conclusion​

The Fosi Audio DS2 is a standout portable DAC/amp, combining high power output, transparency, and platform versatility in a compact, sleek design. Whether you’re driving sensitive IEMs or more demanding over-ear headphones, the DS2 delivers consistent performance without breaking the bank. For audiophiles seeking a reliable, pragmatic solution for portable audio, the DS2 is an easy recommendation.

FOSI AUDIO DS2



INTRODUCTION

The Fosi Audio DS2 version 2024 represents the current most popular portable DAC dongle trend of using a dual CS43141 chip, just like the Moondrop DAWN Pro I also own, so I'm going to base much of my review on a comparison of these two portable DACs.

SOURCES

I typically listened via USB Audio Player Pro in exclusive (Bit-Perfect) mode to files from the TIDAL streaming service, and local files in FLAC format.

PRESENTATION



The DS2 came to me in a small, simple package, packed securely in foam, sitting by itself in a cutout that fits the size. It comes with a thin black-gray USB-C - USB-C cable. Here I would like to point out the first similarity to the Moondrop Dawn Pro i.e. the cable from Moondrop, which, despite being a bit thicker, (it spreads by 1-2 mm) overall is very similar. The main difference is the way the USB-C ports are mounted. In the case of Dawn, the ports are flooded with some kind of resin, which allows for minor movement of the connector itself and can cause signal dropouts over time. In the case of DS2, the port is rigidly mounted in a metal housing and shows no tendency to bend, which I think may carry over to a longer lifespan. Unfortunately, I would classify both cables as fragile, and given the portable nature of using these dongles, I would expect something more durable. An example of a good solution in my opinion is the cable from Kiwi Ears Allegro, which is 2-2.5 times thicker and gives a greater sense of durability, so I'm hoping it will allow longer enjoyment of this product. Fortunately, in case of problems, such a cable can be easily obtained from an external source.

In addition, the kit comes with a USB-C to USB adapter, and that would be it.



BUILD

As for the appearance and construction of the dongle itself, although it is quite similar to the Moondrop Dawn Pro, it is about 1cm longer than it, about 1mm thicker, but about 2mm narrower. However, there is one important difference: the DS2 from Fosi Audio seems to be more solidly built than the Moondrop Dawn Pro. At the time of writing this review, the dongle from Moondrop no longer has a volume control button because it collapsed inside the case, which I, unfortunately, can no longer open because it was loose from the first days of use and I had to glue it down – ehhhh, famous Moondrop QC. DS2 performs much better in this aspect. The dongle is solid, nothing is loose inside, and in general, there seems to be nothing to break in it.

Congrats, Fosi Audio, that's how it should be.


The volume control buttons work flawlessly and allow you to change the volume on a 60-degree scale, so you're more likely to find your “sweet spot.”



PERFORMANCE FEATURES

The Fosi Audio DS2 2024 uses a very popular recent module consisting of two flagship Cirrus Logic chips model CS43131.

According to the manufacturer's declarations, we can count on an output power of 130mW for the 3.5mm port and as much as 510mW for the 4.4 balanced port (!!!).

Signal-to-Noise ratio, or signal-to-noise ratio, or in other words, the audio signal quality index here is 130dB, which is very good, because the higher the value of this parameter, the usually better the quality of the signal itself. We now live in an era where levels above 100dB are also quite common in such small, portable devices, and it's great that the DS2 doesn't disappoint in this aspect either. The SINAD, or Signal-to-Noise and distortion ratio, which is the ratio of the total signal-to-distortion energy and noise, is as high as 109dB here, which of course is also a very good result.

SOUND AND COMPARISON

Once again, since I own a very similar dongle, the Moondrop Dawn Pro, in the sound section I will try to present a direct comparison from listening to both of these dongles, but before that, I would like to convey something important:

Both dongles show a very good quality of reproduced music, and power fully sufficient to drive all the iems I have (including the planar Letshuoer S15), and the differences I was able to pick up were minor enough to go unnoticed without critical, detailed listening. I am confident that a potential buyer will be satisfied with any of these devices, and the following comparison is only meant to make the choice easier.

I will start my direct comparison of these dongles with the sound presentation.

In the case of the Fosi Audio DS2, I had the impression that the sound was softer, devoid of sharp edges, and smoother. In the case of the Moondrop Dawn Pro, at times I got the impression that, especially in the high registers, the sounds were rougher - more pronounced. In a direct comparison, however, I had the feeling that with the DS2, the sounds of drum cymbals, for example, were more natural than with the Dawn Pro, where this sharpness took them away from naturalness. As far as technical capabilities are concerned, I think both units perform very well, and only the increased sharpness I mentioned above may cause an impression of more detail in the Dawn Pro's sound, but it's not a big difference. As for the reproduction of the lower registers, I had the impression that the DS2 is a bit more bass-heavy than the Dawn Pro, with the emphasis also mostly on sub-bass. The bass in the DS2 fills the head more, while the Dawn Pro focuses more on the impact of the sound. As for details, I got the impression that more of them were picked up by the Dawn Pro, but I'm not fully convinced that this is an advantage, because at times the amount of sound distracted from the main line of the song, and after all, that's not the point of hearing all the details, but the song as a whole.

To check the output power, I used a 75Ohm impedance adapter, and with my Letshuoer S15 planar connected, the max volume was definitely above the level of normal listening, so we don't have to worry about lack of power here.



A few more words about the differences from the Moondrop Dawn Pro

a) no gain mode switch

The Fosi Audio DS2 2024 does not have a gain mode switch. From listening, I got the impression that it operates in high gain mode all the time, but I am not sure. Pressing the + and - buttons at the same time did not cause any change in sound.

b) no dedicated application with filters and EQ

Fosi Audio DS2 2024 is a pure dongle with a cable and buttons to change the volume - that's it. Moondrop Dawn Pro allows you to control the device from the dedicated Moonkdrop Link app, where you can: adjust the volume, change the gain mode, the possibility to apply 4 pre-installed sound filters and EQ with the ability to, among other things, import presets (Android only), for example, from Squiglink pages. In my opinion, this is a shortcoming that, for those interested in these capabilities, may be a deterrent to buying the DS2. Fosi Audio should consider introducing such an application, especially because its competitors (Moondrop, Tanchjim) already have them and are constantly improving.

SUMMARY

To best illustrate the differences, I have decided to compile them into tabular form below:



CONCLUSIONS

In conclusion, I can once again say that both devices offer very good sound reproduction quality and enough power to calmly drive most, if not all iems available on the market. With a fairly similar price, the main differences that a potential customer should consider are the quality build of the device, where the DS2 excels, and the functionality associated with the dedicated application that Moondrop has. The choice will depend on the user's needs and expectations. For my part, I think this is a very good dongle and I can confidently recommend it as a portable budget DAC.

Fosi Audio DS2​

Fosi Audio DS2

Prelude:
Fosi audio is a brand that quickly won the hearts of audiophiles around the world and beyond. Thanks to their proposals, all music lovers can enjoy high-quality, excellent audio at a very affordable price. They have many successful propositions and some truly outstanding models, such as SK2, a review of which you can find on my blog. Today we will take a look at the latest version of Fosi Audio ds2 version 2024, it is a miniature USB DAC/AMP dongle with huge output power. This time, a dual circuit from Cirrus Logic was used and the whole thing was priced at a modest USD 79.



Unboxing and ergonomics:
In terms of packaging, we have a small cardboard box with black printing. Inside you will find the device itself, a USB C-C cable, by the way, it reminds me of the one from xDuoo link 2bal, instructions and a USB C to USB adapter. It is quite a nice set, and the device itself is a practical, small metal block, of course we have a hi-res audio sticker and an indicator diode. There is also a detachable cable and, what I am personally very happy about, an independent volume control with clearly separated buttons.



Sound:
This is an interesting arrangement, because Fosi Audio does not strive for ruthlessness and dry neutrality, instead it offers us a pleasant and engaging tuning.

Lower tones: They are accentuated in such a way as to remain natural and at the same time engage us and encourage us to continue listening. The bass is engaging and encourages you to have fun with the music. However, this tuning is not perfectly neutral or colorless. fosi audio ds2 is dedicated rather to casual listening, which can be seen in the elastic and dynamic bass generated by this small device. It’s very interesting how cleverly and skillfully Fosi Audio DS2 combines the naturalness and appropriate mass of low tones with the simultaneous addition of a bit of pleasant and engaging warmth. Lovers of lower bands will certainly not feel their lack, and at the same time, people who like naturalness and purity of sound will also not be disappointed.

Mid tones: They were presented in a very vivid and natural way, slightly warmed up, but only to emphasize the realism and naturalness of the mid tones. The amount of information provided to us by fosi audio ds2 is truly considerable and encourages us to continue listening. Although I perceived the vocals as slightly placed in the foreground and pushed ahead of the line. Despite all this, I found naturalness and purity both tonal and musical. Each instrument was correctly separated and presented in a manner consistent with the recording. Importantly, the sound is quite smooth and even, which encourages further listening.

High tones: Importantly, they are not tiring or overwhelming. Instead, the focus was on the smooth and safe nature of the tuning. The quality of the treble itself is very good, although you can feel a lot of warmth in it. At the same time, the amount of details and information presented to us remains at a very high level, appropriate for much more expensive equipment, and not for a dongle costing less than USD 80, which is a huge positive surprise.

Technical layer and stage:
Technically, the fosi audio ds2 is a device that presents a warmer and musical approach to sound. At the same time, the music was allowed to show its authentic and musical character. fosi audio ds2 positions instruments perfectly and shows a lot of information. When it comes to power, it has a lot of it, and when it comes to the sound stage, it is wide and deep enough considering the price at which the fosi audio ds2 was priced.

Comparisons:

fosi audio ds2 VS iBasso DC04pro ($149)
The DC04pro presents a slightly higher technical level and has a larger stage, but considering the much lower price of the Fosi Audio DS2, these differences are fully justified. However, the fosi audio ds2 certainly has more power and is made of a more resistant material, which is aluminum, compared to the glass in the DC04pro. When it comes to the sound signature, in my opinion the fosi audio ds2 is warmer and the DC04pro puts more emphasis on the naturalness of the sound. However, both devices are great and the fosi audio ds2 really plays very close to the DC04pro. Therefore, I recommend checking both devices for yourself.

fosi audio ds2 VX xDuoo link 2bal ($149)
Link2bal has much less power than fosi audio ds2, because it was created at a time when there was no access to such good amplifiers. Link2bal sounds more bassy, has more low end, which is almost immediately noticeable. At the same time, fosi audio ds2 provides a smoother and more balanced sound. For many people, including me, xDuoo link2bal is one of the most natural dongles on the market. However, thanks to less bass and, importantly, less noise with the very sensitive Fosi Audio DS2 headphones, I can rate them very highly.

fosi audio ds2 VS ddHIFI tc44 pro (79USD)
This will be the most interesting choice, because both devices are incredibly good for their budget and, importantly, not only do they cost similarly, but they also have identical DAC circuits. fosi audio ds2, however, has a detachable cable and 3.5 and 4.4 mm sockets and much more power. At the same time, the ddHIFI tc44pro is much smaller, presents a wider and cooler tuning, but its compact dimensions make it a very well-designed device. Therefore, I can wholeheartedly recommend both devices.

Summary:
Fosi audio ds2 is another device from fosi audio that really delights and positively surprises. This is a great miniature DAC/AMP with a good quality detachable cable. It presents a mature, warmed sound with a pleasant, natural and smooth signature. The sound of the fosi audio ds2 is truly engaging and captivating to listen to. What I would definitely like to change is to add information about the current volume level and automatically reset this level to the lowest value each time the device is turned on. This would help increase safety when listening. However, this is not a disadvantage in this price range, it is rather a problem of most DAC/AMP devices without screens. However, returning to the sound, the Fosi Audio DS2 plays really well, so well that it can successfully compete with much more expensive equipment. Therefore, I heartily recommend this device and encourage you to listen to it.