USB: Do the Dante AVIO USB-C Adapters operate with Lightning to USB-C cables, to allow direct connection of audio and power to a iOS device?

No.

The USB-C to Lightning cables do not support the host/peripheral roles required to directly connect the Dante AVIO USB-C Adapter to an iOS device. This is a limitation defined by Apple. With the USB-C to Lightning cable, the Dante AVIO USB-C Adapter will provide power only to the iOS device.

Lightning to USB-C adapters (with USB type-A ports) can be used to connect either Dante AVIO USB Adapters (ADP-USB-2X2) or Dante AVIO USB-C Adapters (ADP-USBC-2X2) to iOS devices. When connected, the AVIO will appear as available input and output devices.

Apple devices with USB-C ports, such as new iPads, can be connected directly to a Dante AVIO USB-C Adapter with a USB-C to USB-C cable.