Douk Audio U2 XU316 USB to SPDIF Interface Review

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.

Specifications

How it compares

At $56.99 the U2 costs $13.00 less than the Douk Audio U2 PRO ($69.99, Standard version). Both list an XMOS XU316, optical and coaxial outputs, PCM 44.1-192kHz at 16-24-bit and DSD64 over DoP on those outputs, and THD+N 0.000008%. The U2 PRO adds an I2S output (PCM to 768kHz/32bit, DSD to 512), a UAC 1.0/2.0 switch for consoles and a replaceable oscillator, in a body of 85 x 79 x 26mm and 220g. The U2 is 40 x 52 x 20mm and 45g, and its page lists no console mode.

The Douk Audio U2-PRO-FC at $249.99, $193.00 more, adds femtosecond oscillators and a dedicated power input, and carries a pre-sale tag. If a DAC and a headphone amp are wanted too, the Douk Audio K5 at $79.99, $23.00 more, says it also works as a USB-to-optical converter, with its optical output live only while the USB input is selected. Who it suits: the U2 fits a DAC, digital amplifier or AV receiver with only optical or coaxial inputs and a PC, phone or Raspberry Pi as the source. The U2 PRO suits an I2S-capable DAC or a console; the K5 suits a desk that needs the DAC and headphone output as well.

Shipping, returns and warranty

• Shipping: Douk Audio's current shipping page says orders are generally processed no later than the next business day and arrive in 2-8 business days, with duties, taxes and customs fees included in the checkout price unless noted otherwise.
• Older shipping terms are still online: airmail at 10-25 days for parcels under 2 kg, DHL, UPS or FedEx at 5-8 days above that, and a line saying the store is not responsible for import duties. Check the delivery estimate and any duties at checkout.
• Returns: ask within 30 days of delivery and wait for approval before sending anything; an approved return has to ship within 7 days. Items need all packaging and accessories and no excessive wear, or the store can refuse them or refund part of the price. Refunds go to the original payment method after inspection.
• Not refunded: original and expedited shipping, duties, taxes and customs charges, unless the law requires it or the store made the error. The return page does not say who pays return postage, and the older refund page excludes mistaken orders and change-of-mind returns from free after-sale service.
• Warranty: 24 months from purchase for manufacturing defects, with free repair, a replacement unit and free shipping both ways for covered repairs. Drops, liquid, DIY repairs, lightning, extreme temperatures and misuse are excluded (partial fees may apply), and damage from weak packing on the way back may not be covered. The older refund page still says 1 year.
• Seller: the site is run by Shenzhen Anba Technology Co., Ltd (Shenzhen, China) and HONGKONG LONGSHENG Import and Export Trading Co., Limited (Hong Kong); support is by email at [email protected]. These terms cover orders placed on doukaudio.com; other sellers apply their own.

For this product, the page lists shipping to US, UK, EU, AU and Other (a destination list, with no warehouses named) and shows Free Shipping, 2-8 Days Arrival, 30-Day Return and 2-Year Warranty badges near the price.