Creating a simple multi-channel AudioProcessor wrapper?

I’ve created a simple audio app that hosts an AudioProcessor (like the standalone filter class). So far so good. But I would like to set the number of channels to be used in the AudioProcessor based on the number of channels selected in my deviceManager. Is this possible? Can I set the processor up so it has say a maximum numbers of inputs/outputs, but only reads/writes to however many are currently selected in the device manger?