To me, it looks like a digital problem (not analog noise). Maybe a driver problem... It could be buffer overflow, although I'm not sure if buffer underflow causes that kind of problem... I
think buffer underflow is only audible when you are recording actual sound.
You can try increasing your
buffer size, or if you are using a "high resolution" setting, try changing to 16-bit/48kHz.
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About buffers & latency -
Computers have been fast-enough for stereo audio recording for many years. But your computer is always multitasking (even if you are running only one application). The digitized audio data-stream flows smoothly into a buffer ("holding tank") and when the CPU gets around to it, it reads the buffer and sends the data to your hard drive in a quick burst. If the buffer fills-up before CPU gets back to your audio application, you have buffer overflow and you get a glitch.
So, it depends on what (and how much) your operating system is doing in the background. It depends on the size of the buffer. It depends on the amount of audio data (sample rate, bit depth, number of channels). And CPU speed can be a factor if the computer is running multiple applications or something in the background (or the OS) is "hogging" the CPU.
A buffer is also a delay (latency). The bigger the buffer, the more latency you have. For basic recording purposes, this is not an issue and a bigger buffer is better. However, if you are monitoring through the computer (such as a singer monitoring herself/himelf on headphones) latency can be a problem for the performer.