Re: Problems with hdaudio(4) on Dell Optiplex-5050

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> [I]f a stereo headphone is plugged in to the jack on the fron tof the
> machine, the audio switches to that jack, but the two channels are
> mixed together in such a way as to cause them to cancel each other
> out on each headphone.

I'll suggest another possible cause, if I've understood the symptom
correctly.

Stereo headphones use three conductors: one ear signal, the other ear
signal, and common ground.  I have occasionally had the ground
connection break (usually for fixable reasons, in my cases).  This
causes the electrical circuit to amount to both ears in series between
the two signal conductors, leading to an effectively monaural sound
that amounts to the difference between the two channels.  If there's a
defect in the jack or its connections (which I can imagine being common
across a product line or manufacturer), this could at least potentially
be responsible for the symptom you're hearing.

Of course, it also could be software, as you suggest.  One experiment
that might help resolve this occurs to me.  When I've had a machine
crash while playing sound, it usually keeps playing the last short time
(50ms?) in a loop.  If you break to ddb while sound is playing, I'd
expect the same thing to happen.  In that state, the driver isn't going
to be changing anything, so plugging headphones in then might help you
identify whether it's a software issue or not.

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