The story for this signal is the following. I've bought an NAD C 356BEE amplifier with an integrated MDC DAC module. It has optical and USB input. The optical is OK, but if I connect the DAC to my PC with USB, then it makes clicking/popping noise at specified times. The click frequency is somehow related to the signal sample rate. For example at 96 kHz it pops in every 2.5 seconds, but at 48 kHz it pops at 30 seconds.
I've played a sine wave, and I've recorded the noise and zoomed in to the waveform. It's a very short signal, about 0.008 seconds. Do you have any idea what it could be?
The amplitude of the noise signal is much higher than the test signal. The length of the noise signal is random (but very short, you hear just a click), but the waveform is always the same for the same test signal.
Different test frequencies cause different error signals. It seems like the error signal is some transformation of the original.