• Upgrade the Digital Link: Keep your current source and add dedicated S/PDIF reclocking before the DAC. U7 attenuates upstream clock jitter and rebuilds output timing from a precise local reference, helping bring out more focused imaging, clearer separation and a more open, natural presentation. Especially useful with computers, TVs and general-purpose digital sources, or where timing or lock stability matters.
• SRC4392 ASRC + Femto Clock: At the core, U7 pairs TI Burr-Brown’s SRC4392 ASRC with femtosecond clocking in a high-spec reclocking architecture built for exacting digital timing. Oscillator jitter is below 39 fs, with instrument-measured THD+N at 0.000006% and SINAD at 147.2 dB—strong measured evidence of U7’s signal purity.
• Choose 96 or 192kHz Output: U7 accepts PCM up to 24-bit/192kHz and lets you choose the fixed output that suits your DAC instead of being limited to one setting. Select 192kHz for high-sample-rate content to avoid unnecessary down-conversion, or 96kHz for DACs without 192kHz support, balancing high-rate playback with broader compatibility.
• Simplify Your Digital Connections: Keep optical and coaxial sources connected and switch between them without reconnecting cables. Whichever source you select, U7 converts and routes it to coaxial, optical and BNC S/PDIF outputs, all active simultaneously—bridging interface mismatches and feeding multiple downstream devices from one source.  
• Engineered Down to the Details: The compact aluminum chassis fits easily into desktop, shelf or full-size HiFi setups. Standard 5V USB-C keeps power simple and leaves an easy path to a linear supply. Pure-copper, gold-plated coaxial connectors resist oxidation, while built-in overvoltage protection supports reliable long-term use.  

• Brand: Douk Audio
• Model: U7
• Digital Inputs: Coaxial / Optical
• Digital Outputs: Coaxial / Optical / BNC
• Simultaneous Outputs: Supported
• Maximum Sampling Rate: Up to 24-bit / 192kHz
• Output Sample Rate: Selectable 96kHz / 192kHz
• Reclocking Processor: TI Burr-Brown SRC4392 ASRC
• Clock: Femtosecond Oscillator
• Oscillator Jitter: <39 fs
• THD+N: 0.000006%
• SINAD: ≥147.2 dB
• SNR: ≥147.4 dB
• Frequency Response: 20Hz–20kHz (±0.1dB)
• Input Sensitivity: 0 dBFS
• Power Input: USB-C 5V
• Net Weight: 235g / 0.52 lb
• Product Dimensions (W × D × H): 95 × 70 × 35mm / 3.74 × 2.76 × 1.38 in
• Package Weight: 443g / 0.98 lb
• Package Dimensions (W × D × H): 190 × 160 × 60mm / 7.48 × 6.30 × 2.36 in

User Manual of the Douk Audio U7

FAQs

Q: My DAC has a femtosecond clock. Do I still need U7?
A: In most systems, yes.
The DAC’s femtosecond clock only covers D/A conversion—it can’t fix upstream jitter or noise. U7 reclocks and regenerates the S/PDIF before the DAC, so it receives a cleaner, more stable input and performs closer to its full potential.
U7 is especially beneficial when:
  Your source is a computer, TV, streaming box, or general-purpose player.
  You use long or ordinary optical/coaxial cables.
  Your DAC occasionally struggles to lock or sounds less stable.
  You need optical/coaxial conversion, sample-rate unification, or source isolation.

Q: What does U7 do and where should it be connected?
A: U7 is a reclocker that cleans the digital signal before your DAC. Connect it as: Digital Source → U7 → DAC.

Q: Does U7 support DSD audio?
A: No. U7 does not support DSD transmission. It supports 2-channel PCM audio only.

Q: Why does my DAC not recognize U7’s output?
A: Make sure your DAC supports the selected output rate. U7 lets you choose between fixed 96kHz and 192kHz outputs to match your DAC; an incompatible setting may result in no sound.
 
Q: My source is 24-bit/96 kHz. Can U7 output 24-bit/192 kHz to my DAC?
A: A: Yes, provided your DAC supports 192 kHz input. Set U7’s output sampling rate switch to 192 kHz.
Q: Can I use all three outputs at the same time?
A: Can I use all three outputs at the same time?