Some people have claimed to hear an improvement with an external clock on a Wiim Ultra, but I do not think it is possible to re-clock the WiiM Amp Ultra with an outboard clock.
When I play from the computer, I'm not sure whether it is using the clock on my Mac, the clock on the optical interface, or the WiiM's clock. However, I do not notice any difference in fidelity when I use the Qobuz software player on my Mac or use Qobuz Connect to allow the player to directly stream from the source, so either it isn't a difference that I can hear, or the WiiM's internal clock is used for both sources.
After that "audio player that lays out the file in contiguous memory to avoid cpu jitter" example from above, this one is my new favourite audiophile trope. "cheap clock on the computer" I giggled.
When I play from the computer, I'm not sure whether it is using the clock on my Mac, the clock on the optical interface, or the WiiM's clock. However, I do not notice any difference in fidelity when I use the Qobuz software player on my Mac or use Qobuz Connect to allow the player to directly stream from the source, so either it isn't a difference that I can hear, or the WiiM's internal clock is used for both sources.