If you get issues with "cracks & Pops" on the sound using Motu Interfaces, check that the " samples per buffer" in the Motu Audio Control is set to 512 ( or lower)
Default the installation get´s it set on 1024, this causes the problem.
Also it seems that the new drivers are to prefered, the drivers that comes with the unit is old, and should be replaced.
The new ones is much cleaner and are actually taking away a lot of old problems , as "Cracks & Pops" etc...