Many, perhaps most VSTs are prone to clicks on sudden envelope changes. It's something you want to avoid. A fast logarithmic change can be just as effective as a vertical jump and may not show that symptom. The other approach would be to move the jump to the nearest zero-crossing, that might eliminate the click.
EDIT:
I handle pops with an external wave editor (Audition) that lets you pull out specific frequencies with great precision.
post edited by bitflipper - 2007/08/17 11:21:02