The new 0.3.1 plugin has the ability to change the default output. There is a bug that appears when the output is changed by an external application. Repro:
1. Have output-A set as default
2. Change default output with an external command, e.g. with 'pacmd set-default-sink "output-B" '
-> The plugin will show the new default output correctly as output-B, but changes the volume for output-A.
Sean Davis referenced this bugreport in commit 1f501d24799fb7b132b1e36e0278ae1c89021bcd
Change default devices when changed from external application (bug #13908)
Thanks for the bug report. I believe this should be fixed with the above commit. Please reopen this bug if this is not correct.
It appears fixed indeed. Thank you very much!