alsa-project/alsa-tools issue #26 was opened from juanpc2018:
$ alsamixer 1.2.2. 
HDSPconf 1.4 from alsa-tools-gui
i dont know why iis called DDS Sample Offset
should be a slider similar to HDSPmixer 
DDS "Sample Offsett", is similar to a PLL with a more aggressive rejection of the external clock signal. IF the external clock coming from s/pdif is better, vs. RME DDS 200pico second jitter clock, it worsens the clock. acts like a blend control: 0% preference for internal DDS clock = 100% preference for external clock, 100% preference for internal DDS clock = 0% preference for external clock.
Issue URL : https://github.com/alsa-project/alsa-tools/issues/26 Repository URL: https://github.com/alsa-project/alsa-tools