JUCE can easily open multiple audio devices, but keeping their callbacks in sync is a whole other story. With JACK’s recent decision to focus its development on Linux only, we are beginning to run low on cross-platform ways to combine audio devices.

I learned in another thread that there already is an AudioIODeviceCombiner written for the CoreAudio DeviceType. I know that combining audio devices might not be a common use case, but I still think it could open up a lot of possibilities if the AudioIODeviceCombiner class could be generalized and made part of the API, especially considering the fact that there already seems to be some kind of base to the idea in JUCE’s codebase.