It's a
JST NH connector. This connector family is by far the most used on Japanese arcade boards.
To make a headphone harness you need #H4P-SHF-AA (housing) and #SHF-001T-0.8BS (contacts). Unfortunately for US folks there are no low quantity sellers (I know of) of these parts in the US. Digikey only stocks the
contacts and the
3-way housing. If you want other parts you need to buy thousands.
You could try ordering samples from the JST website.
Or here's a link to a UK seller:
http://www.neo-geo.com/forums/showpost.php?p=2862336&postcount=6
A floppy drive power connector works somehow but not too well. It doesn't go all the way in, the pins are shaped very differently from the JST ones and don't make good contact with the header on the board. It's a ghetto solution for lack of a better one.