I'm using a MOTU 896 to record some musc and I'm also using a Blackface ADAT (with a dead transpot) as an A/D converter to add 8 extra channels via the Motu's lightpipe. Do I need some sort of external sync to phase lock the two devices or should I be able to lock the ADAT to the MOTU with the ADAT in.

I know I don't need external synce with a digital mixer but I'm not sure about an ADAT when I'm not running any tape.

Any help would be appreciated. If this doesn't work then it's off to rent an A/D converter.