Pyramix tends to cycle through 44.1kHz PCM when starting up. This causes devices to click and pop because their sample rate is different than the software, or the DAC pops when switching to match the software's sampling rate (and again when it settles back to where you had it). It doesn't seem to matter what the default sample rate is in Pyramix. This may be the cause of the noises you're hearing.
You can try switching the setting in Aneman for your DAC to follow the sampling rate of the software (or not), and see if that reduces the noises.
Several of us complained about this years ago, but it has not changed. It wouldn't hurt to send a message to
support@merging.com to prompt a fix, especially if this solution doesn't work.
Cheers,
-c