Product Overview & Control Functions
Operation Instruction
High and Low Level Mode Switching
Indicator Light
Cautions and notes
Warranty Information
About Fosi Audio


Thank you very much for purchasing the DS2 headphone amp.
Please read the instructions carefully before using the product.
If you have any problems or suggestions for the product, please feel free to contact us via email. We are always at your service.
Email address of our technical support team:support@fosiaudio.com.

DAC Chipset

Dual ESS ES9018K2M QUAD DAC Chips


Output Power

SE: 120mw(32Ω) BAL: 250mw(32Ω)





Frequency Response

20HZ-20KHZ +/-0.5dB



Up to 32bit/768kHz





Dynamic Range



Recommended Headphone Impedance

16~300Ω(SE); 16~300Ω(BAL)


Dual Headphone Outputs

3.5mm single-ended,4.4mm balanced output


Supported Devices

Mac\ Windows\ iOS\ Android


Product Name





Operation Instruction

  1. Connect the DS2 to your Android phone using a USB Type-C (Note: Some Android phones or music players may have compatibility issues due to system and hardware differences, and some phones require the OTG function to be enabled in order to use the DS2 properly.
  2. When connecting the DS2 to a device with a lightning connector, use a lightning to Type-C OTG. (not included in the package)
  3. When playing music on your computer, please select Fosi Audio DS2 as the audio output device for your
  4. Volume control may not be available for some devices in exclusive USB audio access
  5. The DS2 does not have a built-in battery, so the DS2 draws power from the main unit via the USB port. Actual power consumption is related to operation and the device system. The DS2 has built-in audiophile-grade DAC chips. It is normal for the DS2 to get hot during use.

High and Low Level Mode Switching

Click the volume up and down buttons simultaneously once to switch between high and low level mode.

Indicator Light

Cautions and notes

  1. If the DS2 is charged via USB from a mobile phone or computer, it will consume their power.
  2. The DS2 uses a high performance DAC/Amp chip and it is normal for it to get hot during use.
  3. Please adjust the volume to the right level before wearing the headphones to protect your hearing.
  4. Please do not wear headphones when plugging them in or out to avoid sudden impulse noise that may damage your hearing


Q1. Regarding heat and power consumption.

  • The DS2 does not have a battery and therefore consumes power from the device. When connecting the DS2 to a mobile phone or other device, please plan power consumption wisely.
  • The DS2 is small in size but has a high output power. The temperature rise is about 15°C during operation. It is normal for it to get a little warm during use.

Q2. About the support of DSD files in DS2.

  • To play DSD files on the Android devices, please use an APP which supports DSD files (e.g. “HiBy Music APP”) and enable the exclusive USB Audio Access Mode. The DSD output option should be set to DOP or Native. DSD512 is only supported in Native mode.
  • To play DSD files on the iOS devices, please use an APP which supports DSD files (e.g. “HiByMusic APP”) and set DSD output option to (Note: iOS devices cannot support DSD512 currently.)
  • To play DSD tracks on the computer, please use the software which supports DSD files (e.g. “Foobar 2000 on window or Audirvana on mac”) and install the relevant application plug-ins correctly.
  • Switching tracks with different sampling rates will cause relatively obvious impulsing sound which is a normal phenomenon. It is recommended classify music files well.

Q3. How to use the DS2 as a USB DAC for mobile phones?

 [Android-based phone]: Just use the Type-C to Type-C cable to connect the DS2 to a mobile phone (cable is included in the package).


  • A compatibility issue may occur to certain Android mobile phones or music players due to system and hardware differences.
  • Some mobile phones are required to turn on the OTG function, so as to use the DS2 For detailed settings please consult the support of mobile phones.
  • Some mobile phones may show the “non-certified Type-C digital headphone” You can ignore the message and use it normally.

[iPhone/iPad]: Please purchase an additional Lightning to Type C OTG cable to connect DS2 to iPhone / iPad / iPod.


  • Only iOS 10.0.2 and above are supported. Due to the iOS system itself, Apple devices below this version cannot be supported.
  • Since there is a limitation on the power supply to external USB devices from iPhone, DS2 with high output power may have stuttering or no sound problem at high volume.

Q4. How to use the DS2 as a USB DAC for computers?

[Windows system]

  • The DS2 can be used plug-and-play on window 8/10 and does not require driver installation.
  • Connect the DS2 to your computer using a Type-C to Type-C (If your computer’s USB port is USB A, you can use a Type C to USB A cable to help you with this) (included in the package).
  • Select the Fosi Audio DS2 as the audio output on your


  • Macbook does not require driver installation. Select Fosi Audio DS2 directly as the output device.

Q5. Under what circumstances do I need to download the driver before using DS2 in window system?

  • The computer operating system is window 7.
  • To play DSD songs. (Note: but you do not need to install the driver if you are using foobar and have installed its own Waspi plug-in to play DSD songs).
  • Play PCM 768KHZ songs.
  • When the interface of your device is usb 1.0. When you encounter the above problems, please first contact Fosi Audio after-sales service to obtain the DAC driver, and install it as the instruction to enable the USB DAC function.

Q6. What should I pay attention to when using the 4.4 interface balanced mode?

  • Please do not use any 3.5mm to 4.4mm adapters as this may result in no sound, stuttering etc. during use.
  • It is recommended to use 4.4mm headphones directly.

Q7. Does the DS2 support in-line headset control or answering calls with a headset?

  • The DS2 does not support in-line remote control with a headset or answering calls with a headset.
  • When there is an incoming call, the sound is still transmitted through the phone’s speaker and microphone. You can pick up the phone to make a normal call. Whether or not you unplug the DS2 will have no effect.

Q8. Questions about Exclusive USB Audio Access Mode.

Due to system and hardware differences in exclusive USB audio access mode, some Android phones or players may have some permission conflicts and compatibility issues.

Here is the known situations:

  • On some mobile phones or DSD playback software, the volume buttons on the DS1 body cannot be synchronised to control the volume of your mobile phone, you can control the volume directly from your mobile phone.
  • Some phone power management policies do not allow third-party apps to run in the background by default. This may cause the APP to pause in exclusive USB audio access mode after the phone has slept for a few seconds. You can manually set the app to keep working while sleeping in the phone’s battery management settings.
  • Running other apps in exclusive USB audio access mode may cause lagging or no sound issues. We will continue to optimise this issue. If you are using exclusive USB audio access mode, we recommend that you focus on listening to music. Alternatively, you can exit the exclusive USB audio access mode to avoid this proble

Warranty Information​

  • All Fosi Audio products have an 18-month limited warranty on parts and labor from the date of purchase. Please contact us if you have any problems.

About Fosi Audio​

  • Fosi Audio designs and builds innovative audio products with all your music in mind. Great sound, simple but elegant designs, high-quality materials, and truly useful features are what Fosi Audio is about. We sincerely hope you get as much enjoyment from our products as we’ve had to create them!

Our website: www.fosiaudio.com

Amazon store: www.amazon.com/fosiaudio 

Our Youtube channel: Fosi Audio

Our Facebook page: Fosi Audio

WhatsApp: +8613716612254

Call us: +49 33389171782

After-sale Service and Technical Support Email:  support@fosiaudio.com