Sakto Sir! That's exactly what I was getting on my tweeters. The description I gave to the installer was that it was like someone was "crumpling celophane/plastic". We tried everything, and I mean everything, short of re-wiring the entire system:
Change crossovers to brand new ones
Change amps to brand new ones (same model as before - XD40)
Change speakers to brand new ones (same model as before - XSC62)
Change head unit to brand new ones (different brand - Pioneer)
Change speakers to brand new ones (different model - MS6A)
Change amps to brand new ones (different model - DLS CA41)
None of the first five solutions made any improvements. The crackling sound was still there. The last solution did it for me.
Try getting your amp changed, and I mean changed to a different MODEL, not just a brand new XD40. When I changed to a CA41 - kaboom - sound was gone.
Ended up buying the CA41, and just paid for the difference. Oh and I upgraded my seps na rin to MS6As. Couldn't resist. Kinabit na kasi nila as part of finding a solution eh, so sabi ko wag na tanggalin. Andun na rin eh. Hehehe.
Out of curiosity, where did you get your XD40?