I know this isn't the technical FAQ forum, but I don't know where to turn to with this problem:
I'm running the Kontakt 4 player on two different computers and own several sample piano libraries ( Alicia's Keys by NI, Academic Grand by Acoustic Samples etc.) Whatever library I use, I always have this high frequent crackle sound layered on top of every note I play.
I assume it must be related to settings of Kontakt...but I have absolutely no clue on what to do about it. I've also experienced this problem with Konatkt 3 btw...maybe my speakers are too "cheap"...?
It sounds like you need a good ASIO enabled sound interface. A stock laptop or desktop sound card will usually not cut it for a poweful sampler like Kontakt, you need a decent external USB or Firewire interface that has ASIO drivers published (or use ASIO4ALL).
Take the buffer size / latency way out. The latency will drive you crazy but if you don't hear crackles then the problem isn't any kind of overdriving. When you're done drop the buffer size back to about 256. More latency than you probably want but a good starting point.
Stop as many background programs as possible, as in media indexing (Nero Scout) and realtime anti-virus protection.
Google "DAW optimization" and apply suggestions. Unless you know what you are doing, DON'T defeat services.
I come up against this too occasionally and especially with intensive plugs and instruments so this may help...
I don't know what platform you're using (I use Pro Tools but this doesn't matter of course) and the crackle can be a show-stopper for sure. What I do is change the Sample size (Setup > Playback Engine) to something higher; say, from 265 to 1026, click okay, then change it right back again to what I was using formerly. Without technical jargon, it's almost like something is just stuck in the pipes and this cleans it out fresh. I say this, because often there is no apparent reason for the onset but this always fixes it. If you can live with playing on a higher sample rate then it reduces the chances of the crackles appearing, but if not, doing this may be your own saviour. Also, when I'm using for instance Ivory Grand Piano I will (from inside the instrument plugin screen open) reduce the layers/samples to something really low, depending on what I'm playing and the kind of touch/breadth I need. Then after recording the midi I'll change it up to something higher and then increase the sample size to the highest (Setup > Playback Engine again) and record from the midi to audio track (then de-voice/make inactive the midi track).
I have a pretty powerful Mac Pro and yet this still happens on labour intensive instruments (VSL is a shocker) and with high power-hungry plug counts. So this ain't a long term fix, but if you need to get going on a project and haven't the time to hunt for answers (like on forums!) then this will see you through, even if it's a bit clunky.
ASIO drivers come with sound cards that are designed to also run music software. ASIO for all is for those computers without an ASIO sound card and runs ASIO drivers on the CPU instead of using the mega slow audio processing driver that comes with an operating system. You got to make sure your host is set to use ASIO or ASIOforall. If your CPU cant keep up then you also have to set the latency higher so the CPU has more time to process the sounds but set it too high and you might notice the delay of hitting a key and hearing the sound.