With a decent interface like RME, there is no need to change clocking settings. You simply set your preferred clock source to SPDIF. If the KPA is turned off it automatically changes to internal clock master and also passes this clocking to my digital mixer which is connected via ADAT. So it works in any scenario.
That sounds dandy, Till!
Say, if you turn the KPA back on does the interface then automatically derive it's clock from there, and so on?