AD5755-1 has 4 channels and supports both voltage output and current output mode.
Does anyone know if it's possible to use both modes at the same time? For example use 3 channels in voltage output mode and 1 in current mode? Or 2 channels in voltage mode and 2 in current.
Yes each channel can be configured independently using the DAC control register. So any combination of channels can be assigned as you've outlined.