[Ti] weird microphone issues

[Justin R. Miller]

Hi list,

I have recently bought a microphone headset so that I can voice chat 
more easily.  Initially, the microphone was working fine with 
iChat/Skype when I selected Line In as the input source and had the 
headset hooked up (I have a Titanium with a Line In port).  For some 
reason, though, input has stopped working.  I tested the Line In port 
with another device (a Bop-It, if you can believe it) and it worked 
fine.  So I chalked it up to the headset breaking within a week and 
bought another to be sure.  This one does not get any input either.  I 
can get a normal input from the built-in mic in the left speaker, but 
nothing from Line In with either headset.  I've checked that the mic 
mute button is off and that the input level is reasonable (I've tried 
the full range).  Do I have some corrupted preference or something?  
Any ideas?  These are nice Logitech headsets and I'm inclined to think 
that OS X is behaving weirdly.

-- 
Justin R. Miller
incanus at codesorcery.net