An audio interface is an external piece of hardware that has connectors to plug in microphones/other instruments for recording, listening, or sending out to speakers for live performance. Most audio interfaces also offer midi inputs and outputs, which allow you to connect a midi keyboard/controller to your computer. An audio interface will connect to your computer via a USB/Thunderbolt port (some older ones use different ports, such as PCI, PCIe or Ethernet). Some keyboards have an audio interface built into them and they will require you to download a driver to your computer first. You can find out if your keyboard has this capability by checking the user manual.
We do recommend you use an audio interface instead of the "Built-in Output" (headphone jack) to send audio out of MainStage. Generally the sound does not get “better” by using an audio interface- but it is handy for the following reasons (depending on your computer):
- More headroom for your sound- the ability to push out your audio signal at a much louder level without running into any noise floor issues
- A large master output knob for your rig
- Sending multiple outputs easily
- A slight CPU advantage
- Less strain on your computer since the audio interface is sharing the processing work
Here are some different ways to connect your computer, keyboard, audio interface, and DI box: