The operating system of Lightning device is based on Linux kernel with UAC 2.0 driver included. If your DAC does not require a driver to work under Mac OS X system and it is an USB Audio Class 2 version (support sampling rate above 96Khz), it will most likely be compatible with Lightning device.
The Mytek DSD192 and those using 1st generation of M2Tech USB module are also supported by 3rd party driver integration for firmware V1.11 and above. NOTE: 3rd party driver integration are AS IS, AURALiC will not be able to provide any additional support for the functionality.
The USB DAC running on Wavelength USB firmware cannot use USB playback function due to a confirmed bug of Wavelength USB firmware under Linux. The known effected brands are: Ayre, Aesthetix, Berkeley Audio, Jeff Rowland and possibly others.