[Eoin2000]

Thanks Top Jimmy,

Unfortunately I am still struggling. If I connect the USB to the MAC, it crashes and if I connect it to another machine, nothing happens.

Also Im not sure what you mean by "proprietary cue mix function". I know the protools accepts the UMC1820 as the optical clock source as when its disconnected the protools reports that it's switching back.

Any help would be great

Thanks a million