i know many of the sound generators, sometimes more, sometimes less
parameter controller and envelope attack / release crackle front and rear
even with outboard tone generators...
i think it is the mastering magic
it makes things hear that still went through in the mix
i have a lot of experimenting
cleanest control code (without crackling) programmed in the Korg Legacy!!
i love the MDE-X > no crackle, when play with parameter
the source code is extremely successful!
...just, wanted to re-examine the project, but error message

"XITE reset reload dsp... blabla"
- yes -> XITE crash
- no -> XITE frozen
man man, was nun schon wieder
However, that is not the reason for crackling.
??? now...hours later, i found a connection to the good old problematic workflow in the DSP-folder
see also:
http://forums.scopeusers.com/viewtopic.php?f=1&t=33936
JOHN BOWEN Special_Collection-DSP_missing - DeBug 2015_09_28
i check again, found nothing, except uppercase and lowercase characters of dsp-files...
a side effect by thousands of installations??
...boa, ok, again reluctantly accepted challenge
i rollback the original install dsp-folder > copied the current state > absolute same file except uppercase/lowercase, copy "NO"
and yep, just no more error messages when load zarg or spaceF tools
until the next mystery...