After talking to somebody else we reached the conclusion that it'll be probably easier for that guy to just get that sound card he liked again (the M-Audio one I linked earlier), since it seems it's still reasonably easy to get (and cheap too, at least used). Given we know for sure that it'll make him happy I've decided to just tell him to give it a try again =P

Sorry for all the annoyance XD (this is what I get for trying to help with absolutely no idea of the topic in question)

Keep in mind that M-Audio card only has MIDI inputs, it doesn't have microphone inputs.

Eh, I'll ask him again the exact model to make sure, maybe he clicked on the wrong one since it was in a rush (definitely M-Audio though).

But what are the other two connections from the black cable then? I mean, two of those are obviously MIDI, while the other two look like RCA to me. Are they RCA or something else? Because he just wants to use the audio in/out from the keyboard (he has no interest on using a microphone as far as I know).

Yeah those 2 grab midi data from the keyboard. Earlier in the thread you said you were building out a room, I assumed that was a recording room so you could mic instruments. If you're just using a MIDI keyboard that card will work fine,

Well, I honestly don't even know what his full idea is anyway, besides that he only works with his keyboard =P