I have an external soundcard attached to my PC via USB. I also have a MIDI keyboard which I wish to use to input to the computer. But the soundcard only has SP/Dif in and out. Is what I want to do possible? Ian S
No. It isn't. If the Midi Device has a USB interface then you can plug it straight into the computer and it will expose itself as a MIDI over USB device. Otherwise, you will need a sound card that has a MIDI connector/socket on it. You Cannot connect this keyboard to an SP/DIF connector, well you possibly can, but it won't work. At all.
To clarify a bit: SP/DIF is specifically designed to receive a digital audio steam and MIDI is just control data (there is no actual audio), so the two formats are inherently incompatible.