How do I set up null-sink and capture to route audio into camilladsp?

I am trying to set up an assistant on my raspberry pi, but I need the audio to route through camilladsp before it's outputted to my DAC. I figured a pulseaudio null-sink and null-sink capture would be the best/easiest way to do this. (I tried also loopback previously but that was a lot more of a mess). I have set up the null and it is set to the default output, all I need to do now is configure camilladsp to accept the null-sink capture as a capture device, but it is asking for it to be of type: Alsa, File, or Stdin. Any idea how to sort this out, or have an alternative idea for routing the audio through camilladsp? Many thanks, Elliott