After a little further investigation, I found that timidity
was being started by systemd by falling back to /etc/rc*.d/ SYSV
files.
Note that I had removed timidity-daemon, but I did not purge
the package. As a result, it seems that timidity was being
started:
# systemctl list-units "timidity*"
UNIT LOAD ACTIVE SUB DESCRIPTION
timidity.service loaded active running LSB: start and stop timidity
So if you have had timidity-daemon installed at some point, then
be sure to purge the package.
I see that timidity "Suggests" timidity-daemon, although it is not
needed in desktop installations. I imagine that it how it got installed
here some years ago.
The other issue is why timidity is locking out other sound applications
from using plughw:. Perhaps that would be reasonable when
timidity is actively playing sound, although I think most sound
aplications are not so antisocial. I have not looked at that aspect so
far.
