* Paul Davis [2010-04-29 16:43]:

> use a h/w mixer control application (e.g. the ugly and terminal-based
> but-so-far-unmatched alsamixer) to set the capture source of the device back
> to, perhaps, "line in". then later, switch it to the "mic".

Thanks, that worked. Strange thing is I actually had to set the capture
source first to "Stereo Mixer" and then to "Mic" - the other sources
(CD, Line, Front Mic, Stereo Mixer, or setting "Front Mic" and then
"Mic") all exhibited the same behaviour, but setting it to "Stereo
Mixer" and then to "Mic" and leaving it there allowed starting jack with
nothing connected to any jack. I wonder why the source selected *before*
switching to "Mic" matters!

Also, it seems there's no need to connect an actual mic - connecting just
a 1/4" to 3.5mm adapter works just as well. I think I'll just leave it
plugged in.