Fosi audio DS1 Dongle-DAC/Amplifier

FOSI AUDIO DS1: PLUG & PLAY...

1. INTRO​

• Before starting the review, I would like to thank Fosi Audio for sending this unit for review.
• Disclaimer: This review is purely my own opinion based on my experience of using it for several days without any interference from others.
• For this review, I used the Kinera Celest IgniteX Beast iem & Tripowin 4.4mm cable.

2. User Experience​

• First, the build quality, the DS1 is made of a fairly solid material, namely full metal or if specified it is called Tin Alloy. In addition, the DS1 has a fairly heavy weight & also sharp corners so it must be considered again in its use. The quality of the C to C cable is quite good, long & flexible enough so that it is more comfortable to use.
• Second, regarding features, the DS1 can be said to be a plug & play dongle because the features offered are very minimal. The only thing that seems useful is the independent volume feature, the rest just seem like decoration like the high performance feature. My suggestion would be more useful if this feature was replaced with a gain switch.
• Third, in terms of temperature & power, this DS1 has a relatively warm temperature but is still within reasonable limits, not to the point of causing an over temperature or making it uncomfortable to use. While in terms of power, it is also quite ordinary, not economical but not wasteful either. During 1 hour of use using a 4.4mm cable with a volume of 40-50% I used up 10% of my cellphone battery.
• Lastly, regarding power, this DS1 has quite good power but not over power either, it should be good enough for most IEMs. I tested it with the IgniteX Beast with its stock cable at a volume of around 50% which was comfortable enough for my use.

3. Sound Quality​

• For me, this DS1 has a slightly warm neutral characteristic, with a tendency towards the musical rather than the analytical.
• From the bass, when I installed it on my IEM, this DS1 felt like it added a little quantity. The subbass feels a little deeper, while the midbass feels punchier but still well controlled. Overall, the bass feels a little more fun than the initially boring bass on the IgniteX Beast.
• The mid of the DS1 makes the mid of the IgniteX Beast more substantial. The vocals become smoother, more swinging, a little thicker & more natural.
• The treble feels smoother but not too smooth or cut treble. So it feels better for long listening.
• Technically, there are not many changes, only the stage feels a little wider & the separation is a little neater.

4. Comparison​

• Fosi Audio DS1 vs Akliam PD6: PD6 is clearly better in terms of user experience because it offers more complete features. While in terms of sound, both have different directions, PD6 feels more neutral with minimal MSG or not much change in tonal direction, while DS1 is more towards the warm which makes the sound feel more musical or more fun, especially in the low to midrange area. In terms of technical PD6 is clearly better, feels better in many aspects than DS1.

5. Who is Fosi Audio DS1 suitable for?​

• Suitable for those who need a simple plug & play dongle, who don't want to bother with settings.
• Suitable for those who like a slightly warm sound direction.
• Suitable for pairing with a slightly bright IEM or one that has a slightly thin tonal weight.

6. Conclusion​

Fosi Audio DS1 is an interesting DAC dongle in terms of sound & can compete with competitors in its price class. But it is very unfortunate to be honest for me in terms of features or user experience offered by this dongle is less competitive for its price class, where many of its competitors offer much better features & user experience. But it all comes back if you don't need those features, this dongle is perfect because it has sound that I think is good for the price.

★ Introduction :-

Fosi Audio has made the budget dac amp segment much more competitive by releasing quality gear at affordable prices. I used their Ds2 dongle which was pretty good considering the price. Their most hit product was the sk02 dac amp which ranks among the standard sub100$ bucks.Today I'm mainly here with a review of their previous model dongle dac Ds1. I've been using it for more than a month. I'll try to give my personal opinion about it in this review. So that it is convenient for understand how equitable for this price category.

★ Disclaimer :-

This unit was sent to me directly from @Fosi Audio for review purpose. I had no financial agreement with them to promote their product. As always the entire opinion of this review is completely my personal.

★ Box Content at a Glance :-

The packaging of DS1 was quite simple, a flat box of black color contains dongle dac, usb A adapter, user manual and a nice looking nylon braided type c to type c short cable. All useful accessories are available out of the box, so there is no need to buy anything extra. Fosi has no room to complain in this regard




1. Ds1 dongle dac ×1
2. Usb A adapter ×1
3. Type c to type c short cable ×1
4. User manual guide ×1

★ Design, Build Quality & Functionality :-

In terms of design, this dongle does not offer anything impressive, but in the build section, it must be called rock solid. This dongle of fully metal constructed which is a little heavy in weight but feels very durable when held in hand. To me it felt like holding a small metal bar in my hand lol. Apart from the solid build, the compatibility of the device was also excellent. I have used it with windows, android, and ios without any issues. Interestingly it has support from pcm format to native Dsd 512 which was really commendable. The device has a small light indicator that changes color according to the audio sample rate. Moreover, the dongle has a hardware level volume control button whose positioning and pressing feedback were quite satisfactory and at the same time the ports were very strong. From this point of view, fosi audio undoubtedly deserves praise.

★ Specifications :-

~ Model :- DS1
~ Output Power :- 120mW(SE); 220mW(BAL)
~ Terminating Impedance :- 16-300Ω
~ Input Mode :- USB Type C
~ Output Mode :- 3.5MM + 4.4MM Headphone
~ Frequency Range :- 20Hz-20kHz (±0.5dB)
~ THD :- 0.0006%(32Ω SE); 0.001%(32Ω BAL)
~ SNR :- ≥120 dB
~ Sampling Rate :- 32bit/768kHz
~ DSD :- DSD64/128/256/512
~ DAC Chipset :- ES9038Q2M
~ Material :- aluminium Alloy
~ Device Weight :- 38g

★ Tested With :-

~ Sennheiser HD660S2
~ Sony IER M9
~ Tanchjim Origin
~ Dunu Falcon Ultra
~ Hidizs MP145
~ IO Audio Volare
~ NF Audio Ra15
~ Letshouer S08
~ Artti Audio R1

★ Sound Aspect :-

Ds1 basically neutral to slightly warmer sounding dongle. The dongle is able to deliver commendable sound performance from its compact form factor. The low noise floor of the device is relatively quiet, due to which there was no unwanted circuit noise in the background which can be called dead silent noise floor. Due to the lower noise floor, it is able to create a fairly clear invitation to lower frequency sounds naturally. Despite being a performer in the affordable price segment, there was no roll-off issue in its sound which is a big strength. Ds1 dongle has regular single ended port as well as bal port from where the device can show its max output capability. Maximum IEM's or some moderate demanding headphones can be powered up with this Bal port to get more juice out. The dongle has support from pcm to native dsd 512 also supports 32bit/768kHz sample rate. The Dsd playback is not as expected from budget dongles and this was no exception here. The dongle has a small light indicator that changes color based on the sound sampling rate but most of the time it creates a confusing situation that can seem a bit annoying. Talking about the sound, let's talk about the bass at the beginning. The bass section was very tight & impactful, there was good control from sub bass to mid bass area with the body was very pronounced. Bass notes seem to be well-separated where I didn't notice any unwanted bleed issue but the speed is on the good side even though there is a slight lack of texture. Definition was decent enough but definitely not like premium dongles. The Mids region it's completely clean with slight warmth effect which giving a welcoming factor there. It's able to represent the singer's vocal very beautifully without any harshness or dryness. Afterward maintaining the cleanliness of the upper mids, it has managed to ensure the transparency of the lower mids admirably which surprised me. Most of the dongles I have used around this price range have faced problems like mids section being more forward or recessed in many cases but Ds1 is in a far better position compared to them at least for its midrange performance.Treble is basically detailed with good amount of sparkle presence but not very resolving. There was minimal glare which made it somewhat fail to portray the actual character of the sound like cymbals & string instruments. Notwithstanding the extension of Treble was good, but the end to end extension was not that up to the mark. In terms of technicalities, the dongle has given simply excellent performance. Along with wide sound stage, good depth and precise imaging has given a good advantage in terms of fps gaming. Dynamics and macro dynamics punch are decent and there was no complaint about the resolution. So it can be said that under 100$ bucks it will be technically far ahead of its other competitors undoubtedly.

★ Synergy and Power :-

ESS's ES9038Q2M is used as a dac chip in the device, but its sound is not like the typical "ess" house sound. This neutral to warmish sounding dongle has good synergy with almost all types of IEMs.I did not find any decrease in the output power of the device, 120mw@32 ohms from single end and 220mw@32 ohms from Bal port. Despite having such impressive output capability, the dongle is very battery efficient. While using the phone I noticed a very low battery consumption rate which deserves a lot of praise. With this admirable power output, it is possible to power up some demanding headphones in addition to regular dd & planar sets. However, pairing with highly sensitive IEMs was not very well, hissing issue comes easily from here.Because of this, the chances of benefiting from using sensitive sets are very less. I have paired many IEMs with the dongle and even used the full size open back headphone HD660S2. The dongle was able to drive this open back headphone quite well, providing good control by keeping the impact fairly tight in the bass region with decent speed & tolerable staging even can present the mids with fine detail without being harsh. Moreover, treble has mediocre detailed presentation but lacks a lot of dynamics & resolution which is normal to get from such a budget dongle.

★ Conclusion :-

Barring a few minor issues, the ds1 offers everything in its sound performance. It's possible to get good synergy from it everywhere without a very bright sounding set. It can be an ideal option for those whose budget is around 100$. I'm hopeful that the device will be a complete package with solid build, sound quality & high output power that will satisfy most of the listeners. I would suggest to buy it for those who want good technicalities with fun relaxed sound. If someone is looking for something highly technical and analytical sounding dongle then would be advised to stay away from ds1.

I've provided the purchase link below for everyone convenience

FosiAudio Ali express store (link isn't affiliated)

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Video version of this review.

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Build & Design

The first thing you'll notice when taking this thing out of the box is that it's an absolute unit at 37.9 grams, minus the cable.
For it's size it feels incredibly robust, weighty, instilling confidence that it will survive more than a few drops over it's lifetime.

Edges and corners are only ever so slightly chamfered, so it doesn't feel sharp, but it plays strongly into the brutalist aesthetic, with it's asymmetrical raised plug hole mounds and straight lines, which helps this dongle stand out in the sea of curved, smooth aluminium and plastic alternatives.

Like many other dongles it also 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.




The position, brightness and colours of the lights are not obnoxious, but we'll talk more about the colours later.

The USB-C socket provides a reassuringly tight grip on the cable, which in of itself feels like it might be the least robust element.
Perhaps I'm wrong about these twisted 'rope' type cables, but I am concerned about their longevity.
In the end, I think you can be forgiven for believing that USB cables like this are more like consumables, akin to ear pads, which will eventually wear out, break and need replacing in the future.

I'm more in the camp that believes cables should be built to spec for their purpose and extra effort should be made for a cable that potentially may involve many journeys in pockets, being involved in miniature tug of wars between a mobile phone and a headphone cable and potentially many hundreds of plugging cycles.
I hope this one does last, but I'm not yet convinced.
In any case, the presence of a detachable cable rather than a hard-wired cable is always welcome and preferable.

Also provided is a USB type A to C adapter which has the same plastic finish as the cable connectors, but finished in black instead of the grey of the cable.



The volume buttons are symmetrical, making them difficult to differentiate in some situations, particularly on-the-go if it’s in your pocket. So you may need to actively remind yourself that volume up is on the USB side, and volume down is towards the audio sockets.
If used with a laptop, the dongle is very likely to be orientated in the 'correct' or ‘intuitive' direction for volume controls with volume up at the top.
To give credit to Fosi - these buttons have a very satisfying tactile click when pressed, which is always appreciated as each click changes volume by 1 increment out of over 60, but holding the buttons will also slide the volume up or down faster.

As a final side-note, the dongle does get a little warm to the touch after a while but it never reached an uncomfortable temperature.

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Functionality

So let's talk about the LED colours and what they mean.
I found them all relatively unintuitive, so some reading of the manual is required to learn what each colour indicates.



Flashing Red or Yellow indicates the stream is in UAC 1.0 mode.
All other constant LED colours are in UAC 2.0 mode which is preferable, mostly because flashing lights are annoying.

For Most users with a library of mp3s and 16 bit FLAC files, get used to seeing Red and Yellow, as they will most likely have a sample rate of 44.1 and 48kHz.
If you have a library of 24 bit FLACs with a higher sample rate, you will likely see Green and Cyan, and those with DSF files with very high sample rates can expect to also see Blue and Purple, once the DSD format decoding automatically kicks in.
So, if your library contains all of these file types, it may become confusing learning what all these colours mean.

Finally a blinking white light means you've reached the lowest or highest volume.

Each sample rate bracket has two modes: High and Low Mode.
This is actually not a high or low gain mode.
It is in fact a setting you should chose depending on the headphone that you plug into it: Low Mode being for a low impedance headphone, between 16-150 ohms, and High Mode for headphones between 150 and 300 ohms.
The DS1 will however not chose the mode automatically. The only automatic change is the LED colour based on the format being streamed.



To switch between Low and High mode, you're supposed to press both buttons simultaneously, but I found that holding down any one button and pressing the 2nd button after a short delay works better.
The High and Low modes are designed to lower the distortion and are are optimized for the two ranges of headphone resistance previously mentioned.

I think in the end, the High and Low Modes are likely not going to be a significant or defining feature for many users.

One thing users will have to take into consideration is that the maximum power of the dongle can only be unleashed with the use of a balanced 4.4mm cable.
The 3.5mm already provides a really good amount of volume, but the balanced 4.4mm output can very easily give you hearing damage if you're not careful.

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Measurements

The DS1 does not seem to impart any tone to the recording and remains perfectly neutral.
I measured a Sennheiser HD650 seated in exactly the same position with several amps and DACs in quick succession and found that the DS1's frequency response was no different to the others.

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Sound

So how does this amp sound?
It's an amp.
It doesn't make any noise of it's own unless you drop it.
So don't worry about it.

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Comparisons

Compared with my trusty old NFB11.28TXO I was very pleasantly surprised with how well this dongle performs with all kinds of headphones and IEMs.
It is strong enough to adequately drive a Hifiman HE-500 even out of the 3.5mm socket, and does an equally good job of supplying power to planar IEMs like the KZ HBB PR2.
I couldn't detect any obvious reason to pick a more powerful amplifier over the DS1 under normal listening situations.
Most of the dynamic headphones I tested also posed no challenge.
I had to turn the volume up significantly higher for my AKG K501, but it was still below 50%, just to give you an idea of how much headroom this little dongle has.
But of course, even at 100% volume this dongle is nowhere near powerful enough for my hard-to-drive vintages like the Pioneer SE-700.



The DS1 is honestly making me start to question some of my more expensive purchases, but for obvious reasons I won't be using this dongle with my hard to drive vintage headphones, which is already way beyond where you would normally draw the line with any dongles.
No amplifier is designed to output maximum volume all day long, and of course using it on higher volumes with hungrier headphones like full sized planars will also lower the headroom and theoretically increase distortion.
So compared to larger desktop amplifiers, it's better to stay reasonably well within it's recommended specs, but most users of course will not be powering their Hifiman HE-6 or Pioneer SE-700 with this dongle.

It's also worth mentioning that there is absolutely no background hissing or audible distortion at the maximum volume.

Also, aside from the obviously higher power of the 4.4mm balanced output, I didn't hear any obvious reason to use this dongle exclusively with balanced cables.

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Conclusions

This little dongle is capable of powering most common headphones very adequately, while decoding some of the highest quality audio formats around today.
Putting aside any of the design features that may come across as unintuitive or a require a learning curve; in it's purest form there is nothing to strongly dislike.
For minimalists or frequent travellers, this could very easily replace a full sized desktop amplifier, permanently.

I can easily give this product a recommendation based only upon it's audio quality and high power output, but I still have some reservations about the LED colour choices and the USB cable.

If like me you enjoy brutalist design and seemingly endless portable power, this is one dongle worthy of consideration.