The cable most commonly used is the
Edirol UM-1EX. This connects from the PC's USB port to the BFD's Midi input. Has nothing to do with the soundcard.
The only purpose of this connection is to pass filters from REW to a BFD through a cable. You can enter them quite easily by hand if you don't want to buy any cable.
You should read
this and
this
brucek