The default SDM gain adjustment was changed from -3dB to 0dB in Build 216 (April 2017).
It was changed because:
- The main purpose of that setting was to manage modulator instability, which was made pretty much impossible as of that build due to improvements in the S-D modulators
- Setting that setting to anything other than 0dB causes a level offset between DSD content played bit-perfect and upsampled/processed DSD content. So if you set your output to DSD256, then real DSD256 files will be “louder” than upsampled Redbook files. This is inappropriate, and breaks volume leveling
- We already have a place to add signal headroom before processing–the Headroom Adjustment section. And that works without producing any inconsistencies from track to track.
It’s possible if for some reason you re-set-up your audio device from scratch recently that it got the new default. But the 1.4->1.5 migration wouldn’t have touched this setting.
If my head were on straight, we probably wouldn’t have had that setting at all, and would use the main headroom setting for all headroom management. The idea of a DSD-specific headroom adjustment isn’t great product design.