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.
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.