I'm having a similar issue too. It started back in November. I started hearing electric crackles while listening to music. Sometimes they lasted for some seconds, other times they were almost non stop. Sent the laptop, as ASUS laptop, to be repaired. They changed the Wifi card, but as soon as I turned on the laptop the problem was still there. I tried uninstalling the Realtek HD driver and replace it with an older one, it seemed to lower the amount of crackles. Right now I am using Microsoft's High Definition Audio but sometimes I can still hear some weird noises. They almost sound as the sound you hear when you plug or unplug your headphones into the jack. I tried all the solutions suggested in this thread but that still seems to happen. On some headphones it is more noticeable than with others.