HiFiBerry Digi+ &ndash; Transformer Version HiFiBerry Digi 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. The standard version features an optical output and an electrical output. Note that this model is not compatible with older Raspberry Pi model A and B units! Skill Level : Assembled and Tested