Realtek PC support has confirmed that the crackling issue is caused by the SiS
671DX+968. chipset present in my laptop. According to them, their drivers are generic, but they cannot guarantee that they work on all systems. Still, they have suggested that I should download a newer beta release (5898), which unfortunately will take a lot of time at 4 KB/s
I'll report my results as soon as I have them installed in my system.