Unlike most multimedia applications that have an internal volume meter, Rhythmbox actually communicates it's internal volume value to Pulseaudio, and Pulse in turn uses that as Rhythmbox's per-app volume. Problem: when Rhythmbox is the only app running, this means that any Main Volume adjustment to PulseAudio is doubly applied to Rhythmbox (since Pulse will adjust Rhythmbox to match the main system volume, which changes Rhythmbox's internal volume setting). So, for example, moving the Main Volume to 88%, will cascade back into Rhythmbox, reducing the in-app volume by over 50%. Note that like with alsamixer, Pulseaudio's per-app audio doesn't actually match Rhythmbox's internal volume. Hence, setting the Pulse volume for Rhythmbox to 88% will set the in-Rhythmbox volume to near 45%. This is a rather unfortunate side-effect, since it means that adjusting volume while playing music with this program is a major pain in the arse, and the only solution that causes no problems is to leave it at max, which unfortunately is a little uncomfortable. Any change to Rhythmbox's in-app volume or PulseAudio's per-app volume will bubble to the other in unpredictable ways. One clear solution would be for Rhythmbox to stop advertising its internal volume to PulseAudio. Another would be if Pulse didn't adjust Rhythmbox's audio when it's the only program present. By the way, if you run one audio program, and reduce Main Volume to 80% (and thus Pulse moves the program down to 80% too), does that result in a total .8 x .8 = .64 total volume adjustment overall?
