Another change we have decided to make is adding support for 12V analog signals (instead of just 5V). Good news: the AD75019 crosspoint switch supports up to 24V. Bad news: the AD8403 digital potentiometer is limited to 5V. But we can use the AD5263 instead, which supports up to 15V. It only provides 3 resistance levels instead of 4 (20 kΩ, 50 kΩ, 200 kΩ), but that should be plenty enough for what we need. And it can be driven by either I2C or SPI. And as mentioned earlier, we will go with SPI.