HiFiBerry Digi+ Pro is a high-quality S/PDIF output for the Raspberry Pi. It uses the I2S sound port that connects directly to the CPU without the need for an additional USB conversion.
You will need a distribution with an up-to-date kernel (at least summer 2016). The drivers are included in the latest versions of most common distributions.
|MPN:||HiFiBerry Digi+/pro version|