Recording multiple channels of audio simultaneously from attached audio hardware has never been easier, and free!

• As simple as recording audio with the built-in Voice Memos app.
• Record from USB, Bluetooth or built-in sound devices.
• Record all channels exposed by the device simultaneously, eg 16 or 32 channels from digital sound mixers.
• Record in full quality or choose custom sample rates and bit depths.
• Record to lossless file formats, like .wav or .caf.
• Play back all audio channels to the same device.
• Export recordings via AirDrop, the Files app, iCloud, or over USB to an attached computer.
• Full support for digital sound mixers that support the CoreAudio protocol over USB, for example models from Behringer, Allen & Heath, Midas, QSC, or Yamaha.

To record over USB from digital sound mixers additional cables might be required. Consult the mixer manual.
Most mixers use USB Type B ports, like MIDI devices and many printers. In that case a USB Type B to USB Type C cable might be needed.
If the iPhone or iPad has a Lightning port, a USB Type B to Lightning cable, also sometimes referred to as MIDI or OTG Lightning cable is needed.