Most of the portable Sony recorders with digital out, have optical out only. My soundcard is coax in. Unless I buy a full size MD unit, I'll need a converter for any cheap portable Sony recorders, but unless the cheap converter option I linked to is good to go, then a full size player it will need to be. This is for one project only and it's not worth paying the prices for the HOSA 276 and the Midiman/M-Audio CO2 units.
OK, after a bit more research, only a couple of early portable recorders / players have optical out, unless modded. Looks like a full size unit then!
The only Sony MD players available in the UK with digital coax out are the MDS-JB920/930/940 series, a couple of MDS-JE700 series units, and some of the high-end units, as far as I can tell with research.
Thanks for all the advice so far.