Just two weeks ago my desktop has started making crackling noises accompanied with stuttering system responsiveness. The audio slows down slightly too. If I play a game, say Overwatch or Subnautica, the problem will arise and become worse the harder it has to work.
I used LatencyMon as advised and found large system latency spikes which was accompanied by the distorted audio and jumpy responsiveness.
The audio stays the same no matter what playback device is connected and no matter which connector port I use - front or back.