You're using VoiceMeeter, correct? Try increasing your buffer size.
Even without actually encoding, just having OBS open means it is performing all the necessary compositing that it needs to create the scene. You have a lot going on, including multiple browser sources (including the notorious tip jar, which can cripple high-end systems due to physics simulations), StreamFX, and spectralizer. Watch your CPU usage as you open OBS and you should see quite a jump up in usage.
Sound, and especially virtual sound routing, requires very consistent audio processing to make sure the samples end up where they need to go within the required timing. The more CPU load you have in the background (i.e. OBS), the harder it is to make this timing, which results in crackling. Increasing the buffer size should help with this, due to requiring the audio processing thread to be called less often, allowing the timing to be met more easily.
Higher buffer will result in a potentially longer delay between the original source and the re-routed audio output. It also has the potential of more timing drift, since there's more room for it to play with before it hits hard limits.
I'm not sure about system interrupts, unfortunately.
No, the problem is not with the sound. The problem is with something that is interfering with OBS or vice versa. Everything is working fine till I launch OBS. Then the sound cracks and the system interrupts appear in the task manager.
So I found the problem. Now everything is working fine no lag and no sound popping. The problem was my camera capture device. For my FaceCam I am using Elgato CamLink with GoPro. Something was interfering with the system that was creating a strange system lag so I had to unplug and plug the CamLink USB for it to resolve.
PS in logs this problem is not visible - or at least I don't see it...
Why I didn't notice it earlier is because I don't use cam when I just work on my overlay and other OBS/streaming improvements. Simple system restart should help but it didn't and I'm not the expert to explain why.
If someone will be in the same situation as I try unplugging all the USB and plug them back in. I have way too many USB devices connected to one PC.
I dont know how to mark that this problem was solved.