Roon can do volume control in-app and allows the user to set "device", "fixed" or "dsp" volume for each device depending on the endpoint's capabiilities.
On my Pi running Moode Roon allows to set any of these in the device settings.
Fixed is well, fixed and thus removes the in-app volume control for the device, device changes the ALSA volume for the Pi's selected sound device, e.g. this...
... and DSP changes the volume at the source stream using DSP. DSP volume seems to be only for Roon native devices using the RAAT protocol (which Roon Bridge does of course).
All is probably explained better in this Roon knowledgebase article.
For my Hi-Fi's DAC I have it set to fixed as volume is controlled at the amp, initally I think it was set to device by default after enabling it in Roon.
In terms of hardware volume my Topping D50s DAC doesn't do software controllable hardware volume (the D50s' internal volume is only controlled with a real remote).
On my Pi running Moode Roon allows to set any of these in the device settings.
Fixed is well, fixed and thus removes the in-app volume control for the device, device changes the ALSA volume for the Pi's selected sound device, e.g. this...
... and DSP changes the volume at the source stream using DSP. DSP volume seems to be only for Roon native devices using the RAAT protocol (which Roon Bridge does of course).
All is probably explained better in this Roon knowledgebase article.
For my Hi-Fi's DAC I have it set to fixed as volume is controlled at the amp, initally I think it was set to device by default after enabling it in Roon.
In terms of hardware volume my Topping D50s DAC doesn't do software controllable hardware volume (the D50s' internal volume is only controlled with a real remote).