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.