On Sun, Aug 12, 2012 at 1:23 AM, Fons Adriaensen <fons@linuxaudio.org> wrote:
If that is true it is completely wrong from the start. Because that setup can't be maintained when a second app starts playing which can happen at any time. Suppose that first (single) app has its volume set to some low value, and PA uses the soundcard PCM gain control to achieve that as you claim it does. Now suddenly there's a second app which wants a higher level. The only way to achieve that is to raise the hardware gain - you can't compensate for a low setting there by sending a louder signal, it would just clip. So PA now has to adjust the hardware gain and at the same time start scaling down the output from the first app. It's impossible to do that in any acceptable way.
Yet that's exactly what it does. And on my system (HDAudio) I have not noticed any changes in the volume of the first stream, even as the "Master" mixer control jumped levels. Maybe ask the devs for details.