I recently installed Guitar Rig onto my computer and when I plugged in my guitar, I couldn’t really hear anything but a whole bunch of crackling. I adjusted the settings and I could hear my guitar but there was a lot of latency (time between when I hit the string and when I could actually hear it on the computer). There was still a lot of crackling when I was playing, and the latency was really bad, so I did a bit of research and I found out that in order to get rid of the crackling when you play (and the huge latency issue) you need to use ASIO drivers with your sound card.
If you click on the file menu, and then go to audio setup, then you should get this dialog box (or do the equivalent in whatever software you are using). Here, in the interface menu on the soundcard tab, you probably won’t have the option for ASIO (if you’re having these problems). If you do have it, select it as the Interface. If you don’t then go to ASIO4ALL, download it, and install it, and then voila, problem solved! (Don’t forget to go back and change the interface to AISO).