well they won't get a USB one, USB is a data port, not an audio port.
5pin din (depending on the equipment it's plugging into) can carry either input or output signals, the best bet for guaranteed compatibility would be one of these
http://www.maplin.co.uk/Module.aspx?ModuleNo=1 022
used with one of these
http://www.maplin.co.uk/Module.aspx?ModuleNo=1 218
you would then have to experiment to see which pair out of the four phono connectors on the lead gave the desired result with the equipment you have.