EDIT: On that note, the next Amiga Expansion kit needs to come equipped with a 32-bit PCMCIA expnsion slot. 
PCMCIA was a card interface for ISA, which is what the Amiga has.
PCCARD was a card interface for PCI, which is what the 32 bit cards are (although they refer to 16 bit PCMCIA as PCCARD as well).
The latest interface is called ExpressCard.
http://en.wikipedia.org/wiki/ExpressCard It is basically a card connector for USB and PCI Express.
I think most of the express cards I have used are USB based.
tbh USB is probably good enough for sound cards.