Firewire interfaces come in two varieties, Firewire 400 (1394a) which use a 6pin connector and Firewire 800 (1394b) which use a 9 pin connector. Most Firewire interfaces offer lower audio latency than many USB units and many can be used with Apple's Thunderbolt to Firewire Adapter. You can use Firewire 400 devices on a Firewire 800 connection using a 9pin to 6 pin adapter cable. Firewire interfaces are still very popular in the audio industry, as it is possible for some of them to be daisy chained together for high track counts. Firewire can sometimes be a compatibility minefield on windows, Scan Pro Audio's technical department has an enormous multi manufacturer knowledge base for firewire compatibility, so please feel free to ask us when you are planning a purchase.