Roland SP-404MK Reference Manual page 19

When using an iOS device with a USB Type-C
1
Connect your iOS device and the SP-404MKⅡ using a USB cable with USB Type-C
ends (commercially available).
When doing so, you can power the SP-404MKⅡ from your iOS device.
Inputting audio from a computer or mobile device
You must make the appropriate settings when inputting audio from a computer or mobile device. For details, refer to
"Inputting Audio from a Computer or Mobile Device (USB AUDIO)."
®
connector
®
connectors on both