I tested my D30 Pro DAC according to user jkim, using the file CMaj.flac as input.
The audio chain was:
NAS (with the file CMaj.flac) --> Ethernet --> Streamer Wiim Pro Plus, full volume --> Optical connection --> DAC D30 Pro, the volume set to -15 dB --> Headphone Amplifier A90 Discrete, balanced input --> Headphones Beyerdynamic DT 900 Pro X
The D30 Pro firmware version was 2.46 (the latest).
The result:
Absolute no clicking sounds, only three parts of low frequency, which indicates no problem with the CirrusLogic CS43198 DAC chips.
I also tested with the DAC volume set to -20 dB but also in DAC mode, no change.