I have a similar issue with the exact same interface. Guitar Rig has pops and crackles, but this issue doesn't exist in other DAWs with the same buffer settings...
Really want this to work, because I like Cakewalk.
Something is definitely not right. I set the buffer ALL the way up to 1024 samples and still stutters, odd... I tried deleting the AUD file, but the issue persists.