Well ...
this is most likely about USB Audio Class(es), abbreviated as UAC . Thus, it is about the capacity of the PC OS and not about the DAC.
In about the same timeframe as USB 2.0 was launched UAC 1 was introduced. It has about the same performance as CD-quality, ie 16 bits (~ 96 dB) dynamic range and up to 48 kHz (CD has 44.1 kHz sampling rate). This is considered maximum what a normal (young) person can hear.
Later on, UAC 2 was introduced. It should be able to handle the so called hi-res audio, 24 bits / 192 kHz sampling rate.
Modern Windows have UAC 2 implemented, but in order to cover for those with older (but not too old) PC, some DAC (and similar) manufacturers also supply drivers for Windows and IOS. Myself, I regard this as a bit of hocus pocus, as those who are willing to pay some n X $100 for a DAC most likely also have a reasonably modern PC - the specific driver is not needed.
When it comes to Linux it is of course more complicated (that's why we are here, isn't it?). Firstly, DAC manufacturers note the marked penetration of Linux (1-2-3 %) and the diversity of distributions. Then also keep in mind the hocus pocus factor ... so, there is not much to gain in developing specific UAC 2 drivers for Linux.
Actually, it seems (but this is far from clear) that most Linux distributions does have UAC 2 included. Unfortunately, there is not just a nice command to use to see if it is UAC 1 or 2. For me, it is unclear if UAC resides in the kernel (claimed by some, seems most likely to me) or in ALSA/ Pipewire.
Then we arrive to the more philosophical issue: is UAC 2 necessary or not? Well, the amount of truly high-res music is very limited. Some hi-res is clearly just up-scaled "CD-quality" which may be better but also does change the content. Up-scaling is some kind of interpolation, done right it may improve sound but always introduces some new artificial info. There is also a variant of exceptional hi-res, called DSD - some DAC:s can handle this, multiples of 2.4 MHz if I remember right.
In summary:
The drivers are for upgrading USB:s in old PC:s.
Without upgrade one gets CD quality, which is about what one can hear.
The upgrade gives access to a very limited amount of hi-res audio files using UAC 2 (which most Windows and Linux already seems to have).
I do agree that it is most annoying with programs (apps) just made for Win and IOS - I have a minidsp (includes DAC:s) where the control program is just for Win/IOS, every time I want to change I have to re-boot into Win. Such control programs one does not want to risk anything, so WINE is not really an alternative.
Link:
https://www.xmos.com/download/sw_usb_au ... _0_0).pdf/