The AD75019 is a 16 input, 16 output analog crosspoint switch, meaning any or all of the 16 analog inputs can be connected to any or all of the 16 analog outputs. Signals can be positive and negative, with a maximum of 24Vpp (-12V to +12V). A 256 bit shift register controls the state of each of the 256 crosspoint switches. Control signals are 5V logic.
For convenience, the entire board is USB powered, and the +12V and -12V rails are derived from this input voltage with an LT1945 dual DC/DC converter and 7812/7912 LDOs to remove any switching ripple. The 5V digital rail is also filtered in an identical way (SX1308 boosting to +7V followed by a LM1117-5.0).
WARNING: There is no input protection (overvoltage, surge protection) or output protection (short circuit) on any of the pins, to avoid distortion of sensitive input signals. If input signals go above +12V or below -12V, or if excessive output current is drawn, the corresponding channels will be destroyed!
Note: the rail sequencer is incredibly sensitive, and I noticed that moisture can tip the symmetric supply out of balance, causing the 5V supply to remain disabled, which leads to a weak bias of ca. 3.7V on the digital suppy of the AD75019. If this happens, clean and dry the board carefully, then try again. If you measure 5.0V on IC2, the entire power supply circuit is working correctly.
For a video demonstration, see https://www.youtube.com/watch?v=JvzLarRLF1c