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Douk Audio U2 XMOS XU316 USB to SPDIF Digital Interface Review

A pocket-sized USB-to-S/PDIF converter that turns USB audio from a PC, phone or Raspberry Pi into simultaneous optical and coaxial outputs, using the XMOS XU316 chip up to 24-bit/192kHz and DSD64.

3.73.7 out of 5 starsUpdated October 14, 2026
$56.99Price checked October 14, 2026
Check price at Douk Audio
Douk Audio U2 XMOS XU316 USB to SPDIF Digital Interface

Our verdict

The Douk Audio U2 is a specialist problem-solver for $56.99: it puts a modern USB input on DACs, amplifiers and AV gear that only accept optical or coaxial. The XMOS XU316 chip handles PCM up to 24-bit/192kHz and DSD64, feeding both outputs simultaneously, with a format indicator for confidence. Setup is genuinely plug-and-play for most systems. Accept the 192kHz ceiling and stereo-only scope and it is an easy upgrade for older digital gear.

Best for
Feeding USB sources into a DAC, digital amp or AV receiver that only has optical or coaxial S/PDIF inputs
Skip if
You need high-rate DSD or PCM above 192kHz, multichannel output, or driver-free DSD on Windows without extra setup
Check price at Douk AudioHow we research

The Douk Audio U2 is a USB to S/PDIF digital interface — a DDC — priced at $56.99. It converts USB signals from PCs, laptops, phones, tablets and Raspberry Pi boards into optical and coaxial outputs, giving DACs, digital amplifiers and home theater systems without a USB input a clean way into a modern source chain.

At its core is the XMOS XU316 chipset in asynchronous transmission, which the maker ties to virtually no latency, stable signal transmission and lower jitter. Supported formats run to 24-bit/192kHz PCM and DSD64 (DoP), with THD+N quoted at an extremely low 0.000008%. Both outputs work simultaneously, and a built-in sampling rate indicator displays PCM/DSD status and rate so you can verify bit-perfect playback at a glance.

The U2 is designed for simplicity: no driver is needed for PCM playback on Windows 10 and above or macOS, and macOS, Android, iOS and Linux are driver-free entirely. The included dual-head Type-A/Type-C to Type-C cable makes it OTG-ready for phones, and the unit is powered over USB at DC 5V. It measures just 40x52x20mm and weighs 45g, so it disappears behind a desk or rack.

Two limitations to check against your needs: the U2 supports only 2.0-channel stereo audio, so multichannel formats such as 5.1, 7.1 or Dolby are not supported, and Windows 7/8 requires a driver for both PCM and DSD. For iPhones or iPads with a Lightning port, use a high-current camera kit; newer Type-C models can use the included cable directly. Drivers and files for Windows DSD playback come on the included USB drive.

Shipping is worldwide with free and expedited options, and cost varies by country. This unit is very light, so it ships airmail in an estimated 10-25 days unless expedited service is chosen. Import duties and customs fees are the customer's responsibility. Free 30-day returns with a full refund and a 1-year warranty apply to all items, excluding orders placed by mistake, man-made damage or misuse, subjective change of mind, and anything else outside the warranty terms.

What we liked

  • Gives DACs, digital amps and home theater systems that only have S/PDIF inputs a modern USB path with zero-loss conversion
  • XMOS XU316 asynchronous design keeps latency low and the signal clean and jitter-reduced
  • Optical and coaxial outputs run simultaneously, so two downstream devices can be fed at once
  • A built-in sampling rate indicator confirms PCM/DSD status and rate for bit-perfect peace of mind
  • Plug-and-play simplicity: no drivers for PCM on Windows 10+ and macOS, fully OTG-ready with the included dual-head Type-A/Type-C to Type-C cable

Worth noting

  • It tops out at PCM 24-bit/192kHz and DSD64 over DoP, so very high-rate DSD and PCM files are beyond it
  • Only 2.0-channel stereo is supported — multichannel formats like 5.1, 7.1 and Dolby are not
  • Windows 7/8 needs a driver for PCM and DSD, and Lightning-port iPhones or iPads require a high-current camera kit for USB

Questions before you buy

What sample rates does the U2 support?

PCM from 44.1kHz to 192kHz at 16-24 bit and DSD64 over DoP, handled by the XMOS XU316 chipset with THD+N of 0.000008%.

Do I need to install a driver?

For PCM on Windows 10 or above and macOS, no driver is needed. It is also driver-free on Android, iOS and Linux. Windows 7/8 requires a driver for PCM and DSD, and DSD on Windows needs the driver and files provided on the included USB drive.

Can I use it with my phone?

Yes — it supports OTG and comes with an OTG-compatible USB cable. iPhones or iPads with a Lightning port need a high-current camera kit; newer Type-C models can use the included cable directly.

What are the shipping and warranty terms?

Worldwide shipping with free and expedited options; this light unit ships airmail in about 10-25 days. Import duties are the customer's responsibility. Free 30-day returns for a full refund and a 1-year warranty apply, excluding orders by mistake, misuse, change of mind and anything outside the warranty terms.

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