When using a guitar interface to connect your guitar to the device you are running Yousician on, there are a few things you must have in mind to make sure it works properly. If the interface is connected incorrectly, it will not be detected as an audio device in app and its input channel will not be used.
As an example, headphones must always be connected when using a guitar interface. To make sure it works properly, you need to connect your headphones to the interface before you connect it to your device.
Here is how you should to it:
1. Plug in your headphones and guitar to the interface.
2. Connect the interface to the device you want to use it with.