U18

About the U18

The Gustard U18 is a high-end USB digital audio interface (DDC) designed for audiophiles seeking cleaner, more accurate digital signal delivery from computers to DACs. It features a second-generation XMOS XU216 USB receiver with 16 cores, supporting native PCM up to 32-bit/768 kHz and DSD512 formats. The device provides full galvanic isolation via a 200 Mbps isolator to eliminate noise and ground loops from USB sources. It employs a proprietary K2 ultra-low-noise clock synthesizer with dual Accusilicon AS338 oscillators, achieving jitter as low as 38 femtoseconds, powered by a low-noise LT3045 linear regulator. The U18 supports multiple digital outputs including Toslink optical, coaxial S/PDIF, AES/EBU, and configurable I2S over HDMI with four selectable pinouts to ensure compatibility with most DACs. It also features a 10 MHz external clock input for synchronization with an OCXO reference. The device uses a large custom toroidal transformer optimized for audio and includes an independent CPLD for signal reshaping to reduce jitter introduced by isolation. Its OLED display shows sampling frequency, clock source, and output status. The U18 is praised for its robust build, advanced clocking, and noise isolation, making it suitable for high-resolution audio playback setups.