# Mac: USB output channels

**URL:** https://in-thread.sonic-pi.net/t/mac-usb-output-channels/4128
**Category:** Support, Help & Resources
**Created:** [June 29, 2020, 9:35am UTC](https://in-thread.sonic-pi.net/t/mac-usb-output-channels/4128 "2020-06-29T09:35:50Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![FrankLieder](https://avatars.discourse-cdn.com/v4/letter/f/c37758/32.png) [@FrankLieder](https://in-thread.sonic-pi.net/u/FrankLieder)
#### Post date: [June 29, 2020, 9:35am UTC](https://in-thread.sonic-pi.net/t/mac-usb-output-channels/4128/1 "2020-06-29T09:35:50Z")

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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?

Thanks,

Frank.

 ![Screen Shot 2020-06-29 at 10.30.36](https://europe1.discourse-cdn.com/flex017/uploads/sonic_pi/original/2X/f/f220a23874b33cfaa904944234210473177c59e3.png)

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### Author: ![FrankLieder](https://avatars.discourse-cdn.com/v4/letter/f/c37758/32.png) [@FrankLieder](https://in-thread.sonic-pi.net/u/FrankLieder)
#### Post date: [July 2, 2020, 12:46pm UTC](https://in-thread.sonic-pi.net/t/mac-usb-output-channels/4128/2 "2020-07-02T12:46:37Z")

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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.