I know this is an old thread, but I had a crackling problem with my new Clarett 2pre when I set it up today with CbB. I found this thread, so perhaps this will help someone else.
The solution was to increase the Latency slider to 8ms. After I did that, there were no pops or scratchy sounds, just music on playback. This was with multiple instances of Kontakt, Omnisphere, and other plugins.
This automatically increased the buffer size in the Clarett driver.
-- Martin