PRO DI Series


PRO USB is the world's first high-end decoder DI that uses a USB-C input terminal to connect mobile phones and computers. It can not only decode lossless music, but also read DSD format streaming music formats.


  • .Built-in UNiKA-PROTM EI9AE3R3 1.25:1 isolation transformer for each channel
  • .Built-in CT7601 USB bridge and CS43131 DAC with headphone amplifier
  • .32bit convert rate and 192KHz over sampling
  • .Compatible with Windows, Mac OS, iOS and Android systems.
  • .Compatible with DSD digital formats and all common lossless and compressed music formats.
  • .Mini TRS jack used to connect earphone or headphone with volume control
  • .Built-in Type-C USB digital audio input connector
  • .The output is equipped with a GND/LIFT switch


PRO USB is a passive DI box specially designed for mobile devices. It is compatible with Windows, Mac OSX, iOS and Android systems. It does not require any drivers to achieve plug and play. It can be used as a signal impedance matcher for mobile devices and built-in headphone amplifier and volume control.
PRO USB is the first to use TYPE-C as the terminal to connect to mobile phone and computer.
The USB audio decoder combines Com True CT-7601SR and Cirrus Logic CS-43131 to achieve 192KHz/32bit performance, and are compatible with DSD digital formats and all common lossless and compressed music formats.
The PRO USB has a pair of built-in UNiKA-PROTM EI9AE3R3 1.25:1 isolation transformer for each channel isolation transformers. The transformer has a special copper foil layer and a dedicated grounding layer, which can ensure the high signal/noise ratio and dynamic sound of the device, and avoid unnecessary Leakage caused by radio frequency interference, grounding interference and potential difference. PRO USB is especially suitable for mobile phone, computer and media player. It converts high-impedance signals into low-impedance balanced signals, which is convenient for extending the wiring distance and blocking interference.
PRO USB has built-in mini TRS headphone monitor output and monitor volume control, which can drive 16Ω~600Ω headphones.




PRO USB is equipped with the most mainstream TYPE-C USB (2.0) terminal to connect to variety mobile devices and computers, and is accompanied by a music beat indicator on the lest side of TYPE-C socket.

There are many TYPE-C conversion terminals on the market, and it is recommended to use qualified the products avoid transmission failures.




Equipped with a mini TRS headphone output jack and a monitoring volume knob at the bottom and right of TYPE-C, 16Ω~600Ω headphones can be inserted for advance and real-time monitoring. The volume knob does not affect the level of the balanced output at the back of the isolation transformer.




When connected to a computer or mobile device, the computer and mobile device will provide PRO USB power, and the blue light "SOURCE ACTIVE“ on the top cover will also light up at this moment.

Please note that the light on does not mean that the audio signal has been connected. Please refer to the instructions on the previous pages to confirm whether your music is correctly transferred to the PRO USB via your computer or mobile device.




The built-in channel independent balanced isolation transformer has solved the potential difference leakage problem. When the system causes a ground loop due to poor wiring, the noise can be eliminated through the GND/LIFT button.

The GND/LIFT button determines whether pin 1 of the output XLR is grounded, grounded when it bounces, and disconnected from ground when pressed.


Circuit principle Passive/Transformer balance output
USB Version & connector  Ver 2.0 Type- C
UAC bridge solution 32bit/192KHz
DAC solution 32bit/192KHz with 2x DSD 
Power supply Powered by PC or mobile phone throuth Type-C
playback connector with LED status indicator
Music beat indicator LED
Output connector 2 x Male XLR through ISO Transformer
Output GND/LIFT switch Shared push button 
Max Output level 0.778Vrms 
Headphone power output 30mW per channel into 32Ω
5mW per channel into 600Ω 
Frequency response 20Hz-20KHz, ±0.5dB
S/N ratio @20Hz~20KHz un-weight >110dB 
T.H.D. @1KHz 0dBV output <0.005%
Transformer Ratio 1.25:1
Chassis 1.6mm/1.2mm steel cabinet and chassis
Surface finished  Durable complex painting
Dimension (W x D x H) 78 x 124 x 46 mm
Weight 0.64Kg
Shipping weight 0.67kg 
Packing per carton 20pcs/14.00Kgs 
Shipping dimension per carton 305 x 283 x 195mm