Sound crackling and distortion, Asus P8Z68-V, Realtek and SB X-Fi Ti

Hello, first I would like to say that I have searched lots of threads about sound distortion, crackling or bad quality and haven't found any solution. Specs of my computer are:
MB: Asus P8Z68-V
CPU: Intel i5 2500k
GPU: GIGABYTE N570OC-13I
PS: Corsair HX650W
Windows 7 Professional 64-bit

Since I bought my computer I started to hear little crackling during listening to music, watching movies, playing games or looking videos on YouTube. Even Facebook pop sound when you get a message is distorted. I have started to search what is the problem and googled any solution. Unfortunately nothing. After a year of torture because I am recording a lot, I have bought Sound Blaster X-Fi Titanium sound card and hoped it would be better, It is not. It is the same as it was. I have even turned off the motherboard sound card in BIOS. Nothing. Does any one know any soulution please? Thank you very much for any answer.

I have a Sonar X2 recording studio.

There is no "one fix" for the problems you have. Each one can be different. Drivers are one item, including video card drivers. Wi-Fi can cause this, close proximity to a cordless phone or cell phone, etc.

Download and run the free DPC Latency checker and see what that shows for your system. High DPC latency (different from audio latency) can be an issue.

If you are using a separate sound card, the integrated does need to be off in the BIOS or they can conflict.

Some types of motherboard monitor programs can cause problems. I have a gigabyte motherboard and it came with a program to monitor and control some BIOS (UEFI) items from Windows. That program caused very high DPC latency spikes in my new PC when I was debugging it for recording.

DPC Latency Checker

I have tryied that program and got very low latency. It was green all the time

Remove the video card and just use the built in i5 CPU Intel graphics (if you have that). See if that makes any difference. I'm using an i5 3550 on one PC and the Intel HD 3000 graphics does an acceptable job for Win 8 and what I need it for.

Update the Intel motherboard chipset drivers.
Disable Internet, etc.