After so many months , I can confirm that the crackling issues I've been experiencing are fixed with the beta drivers provided by realtek (6.0.1.5898) . Finally I can play music without distorsion and popping 
PS: Incidentally, it seems that the drivers enable the "pc beep" slider that was missing from earlier releases (1.81).

PS: Incidentally, it seems that the drivers enable the "pc beep" slider that was missing from earlier releases (1.81).
My Computer
At a glance
Windows 7 Professional (x64)Intel core 2 duo T94004 GBNvidia Geforce GT120M
- Computer Manufacturer/Model Number
- Asus X61SV
- OS
- Windows 7 Professional (x64)
- CPU
- Intel core 2 duo T9400
- Motherboard
- F50SV
- Memory
- 4 GB
- Graphics Card(s)
- Nvidia Geforce GT120M
- Sound Card
- Realtek HD Audio ALC663
- Hard Drives
- Seagate ST9320320AS (320 GB)
- Mouse
- Microsoft Explorer blutrack
- Internet Speed
- 6 mb/s (DSL)
.