This project documents the design and construction of a high-quality sound card featuring USB and optical (TOSLINK) inputs. The USB interface works in device mode, receiving audio from a computer, while the optical input carries SPDIF signals.

A USB isolator (ADUM4160) provides galvanic separation to prevent noise from the computer. Incoming digital audio streams are converted to PCM via USB-to-I2S (PCM2707) and SPDIF-to-I2S (CS8416) converters. A multiplexer selects the audio source, and an asynchronous sample rate converter (SRC4193) handles resampling and bit-depth conversion before sending the data to the PCM1792 DAC.

Design Notes:

USB and TOSLINK inputs for versatility
Ground isolation via USB isolator
Multiplexer required due to converters lacking tri-state outputs
SRC4193 handles both resampling and clock synchronization
TPA6120 provides high-current headphone drive


References / Source:

This project is based on my MSc thesis: https://github.com/sylwekkominek