Hi Steve, Paul, Mark Since I started this thread, I want to thank you for your interesting answers. What I understand is: The capturing/playback is tightly coupled to the same physical device, except one makes it to tie two different ones together by providing an external clock/sync or propagating an existing clock/sync-source. The solution introduced by Mark connecting the s/pdif clocks sounds _too interesting_ for my audio skills, that's why I decided to order an AEB/O-4 for the 9636 as Steve suggested, since the rest of my setup is completely analog ;) and my first goal still is to reduce delay to zero, when recording overdubs with analog instruments. Martin