Mac: USB output channels

Hi. I am relatively new to Sonic PI and loving it so far.

I have a multi-channel USB mixing desk that I want to use for audio output. I’d like to route SP output to channels 11/12 of the desk. I’ve set up Audio MIDI to use the desk as the default audio output and further set channels 11/12 as the Left/Right speakers. (See screenshot)

With this setup the Music (iTunes) app on the Mac plays audio through channels 11/12.

However, SP is forcing audio to channels 1/2. (SP 3.2.2 Mac)

What am I missing?



Having taken a peek around, I assume my problem is actually with SuperCollider… it’s the one generating the built in synths and sending them to the computer’s audio device.