I recently came across a generic looking ESS1688F based ISA sound card that I wanted to start doing some experimentation with. I was able to do some identification with FCC data, and learned it is a "Labsound 770." Some quick Googling netted me the jumper settings for the card... and a new question. There is a header on the card labeled CN3 called the "3D-sound expansion interface."

Any idea what that was originally for?

Currently, there are a couple of jumpers in place on the connector (I'd assume disabling the port)
(http://arvutimuuseum.ee/th99/i/I-L/51744.htm)

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