Spotify Hardware Volume

[williamlawson]

Hi everybody,

Long time user, very happy with Moode. I am running version 8.3.9 on a RPi4 through a Khadas Tone Board as USB DAC using hardware volume control usually set to 100%, mostly with the Spotify renderer.
I have gotten a new integrated amplifier, which seems to be on the more sensitive side input wise. I do not have a lot of room on the volume knob with the full output of the DAC. I would like to attenuate some at the DAC level to get a more useable volume control on the amplifier.
I have set maximum volume of 50% for ALSA and MPD and it works as far as getting more use out of the potentiometer on the amp.

Here is the question:
First up, is anybody running their setups like this? Any idea if this will degrade the quality? 

It should be fine if the volume control is at the DAC level, because it is a modern 32 bit DAC. However I do not know if Spotify really uses the hardware volume control, this is not clear to me from the settings and my doubts stem from this passage in the ALSA settings:
Establish ALSA 0dB level when volume type is set to Software, Fixed or CamillaDSP, or when any Renderers are active.

This seems to imply that the renderers can only use software volume control. Am I right?

Looking forward to your insights!

[Tim Curtis]

What model Integrated Amp?

Yes, all the renderers use their own software volume algorithm but if the DAC exposes a hardware mixer to ALSA moode will set that to the value of "ALSA max volume" on Audio Config. It defaults to 100% (0dB).

Some renderers including AirPlay and Spotify Connect can also use the DAC's hardware mixer directly but that option proved to be quite difficult to manage reliably in moode code and so it was dropped like 7 or 8 years ago.

[williamlawson]

Thanks for the fast reply. It is a Vincent Audio SV-500.  To be honest also with my old amplifier, a NAD C350, I barely ever went past 10 o'clock


I think the output of the Khadas is just a bit high voltage compared to a normal line level. Maybe I will just get some RCA attenuators.

[williamlawson]

Yes, all the renderers use their own software volume algorithm but if the DAC exposes a hardware mixer to ALSA moode will set that to the value of "ALSA max volume" on Audio Config. It defaults to 100% (0dB).

Had a chat with the guy at the shop and he said to lower the DAC input instead of getting attentuators.

Do I understand correctly, that even though Spotify renderer as implemented by moode is incapable of using hardware volume, moode will set the maximum ALSA volume via hardware (e.g. 50%) so that no bit depth reduction is incurred as long as I do not further reduce the volume in the Spotify app controlling the renderer?

[Tim Curtis]

Digital volume whether its done by ALSA using the DAC's internal hardware mixer or by a player application using its software volume algorithm is typically done using 32 or 64 bit precision and almost always with dither on 16 bit samples. This means that there shouldn't be any audible artifacts.