Note that the ZA2 soundcard which twatts mentioned fits is an ISA card. Most modern computers do not include ISA slots since it is an outdated technology. Fortunately for me I have easy access to scavenge old computer parts and built a machine for free specifically for transfers with a ZA2.
I know the Zoltrix Nightengale was popular there for a while and quite inexpensive - not sure how much they go for these days...