Thank you for taking the time to report this bug and helping to make Ubuntu
better. We are sorry that we do not always have the capacity to look at all
reported bugs in a timely manner. There have been many changes in Ubuntu since
that time you reported the bug and your problem may have been fix
The man page is correct; the system-wide conffile was not. That has
been corrected.
On the other hand, the man page still fails to document the preferred
mechanism in Ubuntu, which is default_driver=pulse.
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Man page incorrectly documents 'default_driver' libao.conf option key
https://bugs.lau