He’s talking about the actual standards documents for transmitting audio over USB.
There are different versions of the USB Audio specifications. The 1.0 version is capped at 24bit/96kHz, yes. It is still used for some low quality applications, but the audiophile world moved on to the 2.0 version of the spec years ago and it’s somewhat rare to run across a product that is pinned to USB Audio 1.0 anymore except at extremely low price points.
USB Audio 2.0 supports much higher data rates, and can be stretched to accomplish Native DSD playback (even though the spec does not directly take into account DSD).
ROCK supports both specifications, and in conjunction with Roon supports PCM sample rates (up to 768kHz), DoP based DSD playback (up to DSD256), and Native DSD modes (up to DSD512). This works on hundreds of USB DACs based on the 2.0 standards.
Native DSD support is sometimes patchy on Linux, depending on which DAC manufacturers have done the work to get their DACs supported in the kernel. We take updates from “upstream” pretty frequently, so we are usually up to date on this stuff, but there is often a delay between when a DAC is released + when Native DSD modes are supported in Linux for that device. Until then, it still works in all other modes of course.
Since this product is based on an unusual USB solution that is relatively new, my best guess is that all PCM rates will work, DoP will work, and Native DSD may or may not work until Linux has had enough time to catch up + incorporate support for Native DSD modes on this chip. But I don’t know that for sure–it’s possible that it is already supported, too.
Also–found this on another forum when researching the chip. Can’t confirm/deny the content, I’d want to see this kind of background before making a purchasing decision.