Dave Plowman in uk.rec.audio:

It's used for headphones on domestic and miniature equipment.

Yes. This is where it first saw the light of day, which is what I meant.

It's also the standard for line output on domestic soundcards.

And line or mic input on some too. Used because it's small. IMHO, it's a
dreadful connector for low signal use.

I agree, not least because it is prone to fall out under the weight of its
own cable. Still, it's the best avaliable until I get a soundcard with
digital out and an offboard dac.

I wish someone would make a serious-ish amp with a 'usb-in' socket, so the
computer recognises it as normal, plug n play, digital speakers, bypassing
a soundcard altogether. I suppose that won't happen until the stigma of pc
audio is gotten over.

--
Jim H