You can paste an audio file from an app that supports copying audio to the clipboard. GarageBand for iPad supports uncompressed audio files with a sample rate of 44.1 kHz and 16-bit depth (the standard for audio CDs).
Audio files copied from another app can be pasted to Audio Recorder or Guitar amp tracks.
You can import an audio file from your computer into Tracks view. GarageBand for iPad supports uncompressed audio files with a 44.1 kHz sample rate and 16-bit depth (the standard for audio CDs). You can also import Apple Loops. If the audio file is an unsupported sample rate or bit depth it will be unavailable in the import window.
Use GarageBand with external output devices
You can use GarageBand with external devices, including AirPlay, Bluetooth, and HDMI-equipped media devices. When using any of these devices there is no support of audio input. This means that you cannot record sound with the Audio Recorder or Sampler, and cannot play a guitar with the Guitar Amp Touch Instrument.
After you connect an external device to your iPad, you must set GarageBand to send audio to the device.
When you are finished using GarageBand with the external device, tap the switch Off.
While the "AirPlay - Bluetooth - HDMI" switch is on, an alert appears if you try to record an Audio Recorder or Guitar Amp Touch Instrument, or if you try to record a sound with the Sampler. You can turn the switch off from the alert.