USB audio interface and precision digital-to-digital converter

The U18 is a high-performance USB-to-digital interface designed for audiophiles who want cleaner, more accurate signal delivery from their computer to their DAC. With full galvanic isolation, a second-generation K2 clock, CPLD signal shaping, and support for PCM up to 768 kHz and DSD512, it eliminates USB noise and jitter while preserving timing and detail. 

Next-level USB processing with XMOS XU216

Powered by a 16-core XU216 USB receiver from XMOS, the U18 handles native PCM up to 32‑bit/768 kHz and DSD512 smoothly, resulting in robust, high-resolution performance.

Complete grounding isolation for cleaner signal

A dedicated 200 Mbps galvanic isolator severs any electrical connection to your PC, removing potential noise from USB ports and grounding loops, so what reaches your DAC is purely digital data. 

K2 ultra-low-noise clock with external reference

The built-in second-generation K2 clock synthesizer, supported by dual Accusilicon AS338 oscillators and powered by a low-noise LT3045 regulator, delivers jitter as low as 38 fs—ensuring stable timing and tighter bass. You can also feed in an external 10 MHz OCXO reference if preferred. 

CPLD signal shaping to reduce jitter

An onboard CPLD reshapes the isolated I²S signal, removing timing errors introduced by isolation. 

Versatile high-resolution outputs

Connect via optical (TOSLINK), coaxial (SPDIF), AES/EBU, I²S over HDMI, or word clock (BNC). I²S pinout offers four configurable modes to match most DACs, with full support for PCM768 and DSD512.

Product highlights

• Native USB input (XU216) with 16-core architecture

• Grounding isolation via 200 Mbps galvanic barrier

• K2 clock synthesizer + twin AS338 oscillators (38 fs jitter)

• Supports external 10 MHz OCXO reference

• CPLD-based I²S signal reshaping

• Outputs: TOSLINK, coaxial, AES/EBU, configurable I²S via HDMI, word clock BNC

• PCM up to 32‑bit/768 kHz; DSD512 native

• Four I²S pinout mode

Specs

• USB Input: XMOS XU216, native DSD512/PCM768

• Isolation: 200 Mbps galvanic USB barrier

• Clocking: K2 synthesizer; 2× Accusilicon AS338 crystals; LT3045 regulator; ≤38 fs jitter

• CPLD: Altera MAX II for I²S jitter shaping

• Outputs:

  • Coaxial SPDIF (75 Ω, 500 mVp-p)

  • AES/EBU (110 Ω, 2.1 Vp-p)

  • Optical TOSLINK (≤24‑bit/192 kHz via DoP64)

  • I²S (HDMI LVDS, PCM768/DSD512)

• Word Clock BNC (3.3–5 Vp-p)

• Configurations: 4 user-selectable I²S pinouts

• Clock Input: 10 MHz BNC (0 dBm)

• Power: 115–230 VAC; <10 W consumption

• Build: Toroidal transformer, chassis dampening

• Dimensions: 220 × 170 × 50 mm

• Weight: ~1.9 kg

• Warranty: Typically 1–2 years depending on region

What’s included

• Gustard U18 unit

• Power cable

• USB-A to USB-B cable

• User manual