>>I am brazilian and I speak portuguese, so forgive my english, I’ll use translation tools to help<<
INTRO:
FOSI is a company that stands out for its variety of audio equipment, including amplifiers, DACs, dongles, bluetooth transmitters, CD players, speakers, etc. In addition to the large number of models, FOSI equipments also offers great value for money for the consumer. Today I’m going to take a quick look at the brand’s new DAC/AMP dongle, the FOSI DS3.
Price: $99.99 USD
Colors: Black or Silver
FOSI reviews: IM4.
FOSI LINKS:
https://s.click.aliexpress.com/e/_c35g182p (PC)
https://s.click.aliexpress.com/e/_c4CJR4ev (APP)
SPECIFICATIONS:
– USB chip: XMOS Powered
– DAC: ES9039Q2M
– USB Audio Class: UAC 1.0 & UAC 2.0
– Sampling rate UAC 1.0: 48kHz/16bit (PCM)
– Sampling rate UAC 2.0: 768kHz/32bit (PCM), DSD512 (Native), DSD256 (DoP)
– Input: USB type C
– Headphone output: Single-ended 3.5mm + balanced 4.4mm
– 3.5mm SE output power: L+R≥120mW+120mW (32Ω)
– 4.4mm Balanced output power: L+R≥220mW+220mW (32Ω)
– SNR: ≥122dB (3.5mm), ≥120dB (4.4mm)
– Dynamic range: ≥119dB (3.5mm), ≥116dB (4.4mm)
– THD+N: <0.0003% (3.5mm), <0.0005% (4.4mm)
– Headphone impedance: 16-300Ω
– DS3 weight: 16.3g
– DS3 dimension: 5.5cm [L] x 1.9cm [W] x 1cm [D]
– Cable weight: 4.2g
– Cable size (edge to edge): 15cm
– Total weight (packaging, dongle, etc): 90.9g
– Packaging size: 12.8cm [L] x 8.7cm [W] x 2.3cm [D]
UNBOXING:
PHYSICAL ASPECTS:
Construction:
- Sources: Samsung S22 Ultra, Samsung A36, Dell i14 Notebook (W10).
- Earphones: FOSI IM4, Kiwi Ears Quintet, Tin Hifi P1.
- Product with excellent build quality.
- Made of aviation-grade aluminum alloy.
- No noise in the buttons.
- Aesthetically very beautiful (subjective).
- Front design inspired by watch bezels.
- Embossed body details inspired by vinyl and CDs.
- Entire glass back (showing the circuit).
- Very compact, lightweight, and portable dongle.
- 2 physical buttons on the right side (volume + & volume -).
- LED indicator fixed to the circuit.
- Included USB-C cable is of good quality.
- Comes with a USB-A/USB-C adapter.
- Lightning cable is required for iPhones.
- Doesn’t include a case or protective cover.
- FOSI hasn’t made a case for the DS3 (yet).
- Some care is needed due to the glass parts.
- Glass can scratch and compromise the product’s aesthetics.
Characteristics:
- It didn’t exhibit abnormal heating, only a slight warmth.
- It’s Plug & Play: it recognizes the device automatically, just plug it in.
- It doesn’t support calls (mic and controls).
- Independent volume control.
- Volume scale: 60 steps.
- Remembers the last used volume.
- The indicator LED changes color to signal UAC modes and sampling rate.
- I only use FLAC 16Bits-44.1/48kHz or Spotify, YT Music.
- I use VLC Player (on all devices).
- The DS3 is compatible with iOS version 10.2.2 or higher.
- It doesn’t have a mobile app, only a web app (computer).
- Firmware version: 1.4.6.
Features:
- Volume control: Increase or decrease the volume.
- Gain control: High or Low gain.
- UAC mode: USB Audio Class 1.0 or 2.0. For compatibility with some devices. Ex: Nintendo Switch.
- DAC filter switching: Filters available from the DAC chip.
- Virtual 7.1 Surround: Emulates the spatiality of 7.1 speaker systems.
- FPS effect: Improves gunshot and footstep sounds for first-person games.
- The FPS mode and 7.1 only work in UAC 1.0.
- Web APP: https://cc.fosiaudio.com/
- The Web App offers EQ and equalizer presets.
- Other Dongle functions can be controlled via the Web App.

Content:
- Fosi Audio DS3
- User Manual
- USB-C Cable
- USB-C to USB-A Adapter
- Quick Guide

















SOUND ASPECTS:
- DAC chip ESS ES9039Q2M used in high-end DACs.
- Excellent audio quality.
- There was indeed an evolution from the previous DS2 to the DS3.
- Clean, transparent, and high-definition sound.
- No background noise (or inaudible noise).
- No coloration or distortion.
- Great level of technicality (maintains or improves the earphone’s attributes).
- Regarding the DAC’s digital filters, I personally don’t hear a difference.
- FPS mode: I found it very similar to the normal mode, just a slight emphasis on the pinna gain region. I don’t usually play games, so my experience won’t be very valuable.
- 7.1 surround mode: it really changes the sound, there’s a reduction in the mids, and it creates a sound immersion. Honestly, I think it’s more interesting for someone to equalize based on the normal mode or go for earphones that have this more spatial characteristic (my opinion).
- I understand that the two options I mentioned above aren’t always so straightforward for the average person, so the feature offered by the dongle can make a lot of sense.
Amplification:
- I always used the DS3 on High Gain.
- The best performance is with high gain.
- Low Gain is only really useful if it’s a matter of not draining the phone’s battery.
- I review the sound quality with the dongle connected to the computer.
- The ideal level for me was the DS3 at Max Volume (60) and the computer at 30% (out of 100).
- The IM4 and Quintet are easy to drive; I used them on the 3.5mm output.
- The DS3 pushed the IM4 and Quintet with ease.
- I used the P1 on the 4.4mm Balanced output. Volume 40% (out of the 100 available on W10).
- I listen to music at low/medium volume, so for me it was OK.
- The P1 showed clipping signs above 60%.
- In my opinion, the DS3 can drive most IEMs.
- It will also be sufficient for headphones that aren’t too demanding.
- It’s worth noting that the DS3 isn’t the most powerful in its price range.
- Of those I review, the SMSL D10 had more power on the 4.4mm jack.
PROS AND CONS:
– Excellent build quality
– Very nice design (subjective)
– Power for IEMs and simple headphones
– Web App (browser)
– Hi-Res sound
– Excellent transparency and definition
– No audible distortion
– Great level of technicality
– Doesn’t overheat
– Balanced 3.5mm and 4.4mm outputs
– Good quality USB-C cable
– USB-A adapter
– Very compact, lightweight and portable
– No mobile app available
– Lacks protective case
– Requires care due to glass parts
– Not the most powerful in its price range


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