@Merlot52 AUTO WORDCLOCK should be selected when using the Rossini Clock, MASTER when using the internal clock.
From the manual:
@solwisesteve The Bartók remembers the sync mode you have set separately for each digital input, so if you set it to Audio Sync for SPDIF/ Toslink, and leave it in Master Sync for USB and Network, you are set. The buffer needs to be corrected, when you change source.