This is a expansion board designed for Raspberry pi A + B + designed Specific HIFI DiGi+ adopt Wolfson company high-end digital chip using the 12S interface support 16 to 24 audio data formats and the advanced shake reduction technology could control the Intribsic period jitter in 50ps RMS; Reductive degree is high supporting hardware method of controlling volume and the user can cooperate audio player system to set up their own network HIFI player after using the expansion board. It's convenient that this expansion board also provide two output interface fiber (S/PDIF) and coaxial (RCA) for external device user can get rid of PC power boot off slowly the power supply noise and so on .