Multi channel audio output using audio interface

Hi – appreciate there are a couple of similar questions on this but couldn’t get a resolution that works for playing samples. Wondering if it’s just not possible so any steer appreciated.

I am trying to build a simple 6 channel non-linear audio system in Processing. I use MacOS and a nice MOTU Mk5 audio interface which has 10 analogue audio outputs. I connect 1-6 to 6 separate powered monitors. I am looking to send a sound to play on a specific channel. I can see the interface and separate mono channels in software like Audition and all works well from there – great for linear soundscapes. But I’d like to randomly trigger and control sounds to create a non-linear sound installation framework. I’m confused as to how I set up either the Sound or Minim library – tried various implementations but no luck.
returns a list of outputs and IDs and a count of inputs and outputs for every device eg.

device id 6: MOTU Mk5
max inputs : 18
max outputs: 22

So I can set the audio interface up as the output but don’t know how to address a specific output.

It’s possible it’s not do-able. Just looking for any experience or feedback to confirm. Thanks!

[ update: I can successfully send synth sounds out of separate outputs on the MOTU using info from this very helpful post. Now trying to work out how to play samples