I just updated my pi4 to version 3.512 and now on DSD files there is an accompanying hiss to the music. Before the update all was fine,
I am using a SMSL m400 dac and volumio recognises it as SMSL USB AUDIO. When changing the mixer type from None to Software the hiss disappears. That setting only shows those 2 options. I understand software is not as good.
This is because we did not release this fix on this image. This fix required 2 fixes: our multiroom switcher fix (done) and an mpd update. The mpd update unfortunately broke compatibility of fusion DSP and streaming services. So we concluded that breaking fusion dsp (a widely used and loved feature) was not an option. So we reverted the mpd update.
We are still working on it, which involves going deeper and deeper into the alsa realms trying to spot and fix the regression.