Product Specifications

Fosi Audio DA-2120C is a Bluetooth hi-res 2.1 channel amplifier that features 120W x2 stereo wireless stream aptX, 24Bit/192kHz, compact mini power amp which is equipped with integrated USB coaxial optical DAC input, supporting subwoofer and with a remote control to switch different modes and EQ to enjoy hi-res music!

THD:≤ 0.01%
SNR:≥ 105dB
Bluetooth Name:“BT HIFI AUDIO” or “Fosi Audio DA2120C”
Power Supply:32V 5A
Output:120W + 120W @4ohm
Terminating Impedance:2Ohm – 8Ohm
Frequency Range:20Hz – 20kHz (±1 dB)
Bluetooth Transmission Distance:Up to 28ft
Input Mode:Bluetooth + USB + Optical + Coaxial +RCA
Output Mode:Passive Speakers + Active Subwoofer
System Supported: XP/W7/W8/W10/MAC/Linux
Size:L180*W130*H38mm (7*5*1.5in)

Product Overview & Control Functions

Remote Control


Number Function
1Power on/off
2Mode select:
3Mute on/off
4Bass up
5Treble down
6Treble up
7Loudness on/off
8Bass down
9EQ mode select: Normal/Country/HeavyRock/Jazz/LiteRock/Rap
10Recover: 1. HIFI: Treble and bass initialization; 2. TONE-ON: Restore treble and bass gain.
11Volume down
12Volume up
13Short press to turn off OLED display; long press to adjust sound gain.

Package Contents

Fosi Audio DA-2120C *1
Remote Control *1
Optical Cable *1
PC-USB Cable *1
Bluetooth Antenna *1

Quick Setup


Prepare 1: DA-2120C, 32V power supply, passive speakers, speaker wires or banana plugs;
Prepare 2: Connect the DA-2120C to the passive speakers via the speaker wire or banana plugs;
Prepare 3: Connect the 32V power supply to the DC input;
Prepare 4: Short press the Power Knob to turn on the DA-2120C amplifier.

How to connect the speaker wire?

Method 1: Bare wire connection illustration

① Release the horn terminals block terminals;
② Insert the two ends of the speaker wire into the amplifier and speaker terminal holes.
③ Tighten the horn terminals.

Note: Please avoid the speaker wires being exposed and touching the amplifier casing, as this may cause a short circuit fault.

Method 2: Banana plugs connection illustration

① Release the banana jacket;
② Loosen the screw;
③ Insertion speaker wire and tighten the screw;
④ Tighten the banana jacket;
⑤ Insert the banana plug into the horn terminals of the speaker and amplifier.

Note: Please take care to avoid contact between the two banana plugs and causing a short circuit fault as some of the banana plugs are metal cased.

Bluetooth for example

Prepare: Bluetooth device (Phone for example)
Step 1: Press the Mode Select Knob to select to Bluetooth mode, “BT” display is flashing;
Step 2: Turn on the Bluetooth on your phone and search for: “BT HIFI AUDIO” or “Fosi Audio DA2120C”, connect to the DA-2120C, “BT” display is always on;
Step 3: Open the audio application, play and enjoy!

PC-USB for example

Prepare: PC, PC-USB cable.
Step 1: Connect the PC to DA-2120C’s USB interface via the PC-USB cable;
Step 2: Press the Mode Select Knob to select to USB mode;
Step 3: Click the sound icon in your PC’s notification area; click the “Select playback device” option; select the playback device – SPDIF “Digital HiFi Audio” or “Fosi Audio DA2120C”;
Step 4: Open the audio application, play and enjoy!

Optical for example

Prepare: optical device (TV for example), optical cable.
Step 1: Connect the TV to DA-2120C’s optical interface via the optical cable;
Step 2: Press the Mode Select Knob to select to optical mode;
Step 3: Set the TV’s optical output sound to RAW/PCM.

NOTE: Due to different TV types, some TVs default Dolby or DTS sound output, DA-2120C DOES NOT support Dolby and DTS sound, please select RAW/PCM sound, otherwise you will hear a lot of noise or no sound output.

Step 4: Open the audio application, play and enjoy!

Coaxial for example

Prepare: Coaxial device (TV for example), Coaxial cable (no include).
Step 1: Connect the TV to DA-2120C’s coaxial interface via the coaxial cable;
Step 2: Press the Mode Select Knob to select to coaxial mode.
Step 3: Set the TV’s coaxial output sound to RAW/PCM.

NOTE:Due to different TV types, some TVs default Dolby or DTS sound output, DA-2120C DOES NOT support Dolby and DTS sound, please select RAW/PCM sound, otherwise you will hear a lot of noise or no sound output.

Step 4: Open the audio application, play and enjoy!

RCA for example

Prepare: RCA device (phone for example), 3.5mm to RCA cable (no include) or RCA to RCA cable (some devices will need)
Step 1: Connect the phone to DA-2120C’s RCA interface via the 3.5mm to RCA cable;
Step 2: Press the Mode Select Knob to select to AUX mode;
Step 3: Open the audio application, play and enjoy!


1: Why do I get loud hiss noise coming from the TV via optical input?

  • Please turn off Dolby/DTS audio on your TV or TV App, DA-2120C does not support Dolby/DTS audio input.

2: Why am I not getting enough power from DA-2120C to compare to a 50W x2 amplifier?

  • For low power, please long-press remote: “DISPLAY” to boost gain to +6dB.

3: Can this product be used at 220 volts?

  • Yes, the power supply can work at any AC 110V-240V.

4: Does the DA-2120C support Bluetooth 5.0 & aptX?

  • The DA-2120C supports Bluetooth 5.0 and backwards compatibility with 4.2, 4.0, etc. Also, the DA-2120C supports Bluetooth aptX.

5: Why can’t I use aptX to connect to the DA-2120C?

  • The DA2120C supports aptX but still requires a Bluetooth device e.g. mobile phone) that also supports aptX to work. Please check that your Bluetooth device has aptX enabled or seek support from your Bluetooth device’s customer service for further assistance.

6: Can I use headphone with this product?

  • No, the DA-2120C cannot be connected to headphones and only supports passive speakers or active subwoofer output.

7: Why does the sound is cracking or make a lot of electric noise?

  • Please make sure all the cables completely pushed into the devices, incompletely connection will cause this cracking.
  • Please remove all the inputs then check whether cracking noise disappear or not, the cracking maybe from the audio source or input cables.
  • If you are not using the original factory standard power supply, please replace the power supply before testing. Many power supply in the market have large interference coefficient, which will cause a lot of current sound.

8: My Bluetooth device can’t pair with DA2120C?

  • Make sure that DA2120C Bluetooth mode is on and “BT” display is flashing; “BT” display is always on to indicate that it is connected.
  • Make sure that DA2120C is not paired with other devices.
  • Make sure that the distance between your device and DA2120C is not too long, close your device to DA2120C to have a try.
  • Make sure there are no obstacles between your device and DA2120C, obstacles will affect the Bluetooth operation distance.
  • Please try to change another Bluetooth audio source to test.
  • Replug power supply and restart the DA2120C and then try to connect again, try to use another brand of mobile phone.

9: No Dolby/DTS audio and I still get noise through the USB input?

  • Please switch the USB port to USB 3.0 or back USB port and try again, as some USB ports have unstable data transmission;
  • Please try again with another computer;
  • Please replace the PC-USB cable and retest, contact me for compensation if the original cable is faulty;
  • Please change the power supply adaptation and retest, why? Because of the ageing of the power supply there may be an abnormal power supply resulting in white noise. I recommend using the 9V-32V power supply to test it.

10: USB Device not recognized on Windows?

  • Computer sound setting: Select Start, then type device manager in the Search box, and then select “Device Manager”. Expand Universal Serial Bus controllers. Press and hold (or
    right-click) the DA-2120C (Digital Hifi Audio) device and select Uninstall.  
Repeat for each device to uninstall.
Restart your computer.
Your USB controllers will automatically install.
  • Please try another computer connection.
  • Please try another USB 3.0 interface connection.
  • Please try an alternative USB cable.

11: Why do I get an intermittent sound?

  • Please switch the USB cable to USB 3.0 port or back USB port and try again, as some USB ports have unstable data transmission;
  • Please replace the PC-USB cable and replug power supply to restart the amplifier, contact Fosi Audio customer support for compensation if the original cable is faulty.

12: Can this input through USB, and output to optical with 5.1 surround?

  • It cannot. The optical connection is only an input, not an output.

13: Why is the actual power sometimes very powerful, but sometimes the actual power per channel seems to be less than 120W?

  • The product factory again and again after rigorous testing, under normal circumstances the rated power is completely up to 120Wx2, but the actual use of the product power size and the type of speakers also have a relationship.

14: One channel does not work?

  • Please test whether the Bluetooth and RCA input have the same problem first.
  • If the two modes have the same problem, swap the speaker cables of the left and right channels, or change another speakers, and then test whether this channel still does not work;
  • If only RCA or Bluetooth mode does not work, change the audio source, change the RCA cable and test again, and make sure that all the cables are completely pushed into the device.

15: DA2120C supports subwoofer, is it possible to connect the subwoofer directly?

  • The sub output can be connected to active/powered subwoofer or to subwoofer amplifier then to passive subwoofer.

16: Can I leave the DA-2120C power on all the time? Does it safe?

  • Sure, the DA-2120C is class D amplifier, will cost very low power when nothing playing through it, and it’s safe and you can leave it on all the time.

17: Can I exchange the power supply come with the amplifier and to get more power?

  • The DA-2120C come with 32V 5A power supply, it’s enough for most bookshelf speakers, but if you want to get more power, you can exchange the power supply, the voltage range is DC12-36V, you can use 36V 8A, or 36V 10A power supply or more.

Any problems please leave a message to the customer support email address: support@fosiaudio.com.

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