A common argument I've seen against SPDIF, especially optical TOSLINK, is they sometimes use the incoming data as the clock source, which could potentially have a lot of jitter depending on the source, compared to asynchronous USB DACs which use an internal clock. But I also know some DACs include "jitter suppression" which essentially reclocks the signal using an internal clock. For example from the RME ADI-2 DAC's manual:
The ADI-2 DAC supports sample rates between 44.1 kHz and 768 kHz. Furthermore, RME's SteadyClock FS guarantees exceptional performance in all clock modes. Thanks to a highly efficient jitter suppression, the DA-conversion always operates on highest sonic level, being completely independent from the quality of the incoming clock signal.
How common is this in the current generation of DACs?