Here are the important characteristics of sound cards:
Discrete sound cards are available in ISA and PCI models, although ISA cards are a vanishing breed and are increasingly hard to find. All recent embedded sound adapters use PCI. The much smaller bandwidth of ISA limits ISA cards in many respects, including generally requiring that wavetable data be stored locally, placing an upper limit of about 16 on simultaneous sound streams, and making effective 3D audio support impossible. The first PCI audio chipsets that emerged in the mid-90s were quite expensive, but current PCI cards are generally less expensive than ISA cards with similar functionality, primarily because they require little on-board memory.
FM synthesis is no longer used in current sound cards. All current midrange sound cards use wavetable synthesis, and some expensive sound cards use partial waveguide synthesis. The quality and features of wavetable synthesis vary depending on both the processor and the quality and size of the wavetable samples, with more expensive cards producing better synthesis, as you might expect.
Each MIDI interface supports 16 channels, each corresponding to one instrument. Low-end sound cards use a single MIDI interface, allowing up to 16 instruments to play simultaneously. Midrange and some high-end sound cards provide dual MIDI interfaces, allowing 32 simultaneous instruments. Some high-end sound cards, such as the Creative Labs ...