FireWire requires optional 400 or 800 AMBus card, 2-in (XLR balanced analog mic or line), 2-out analog (XLR), 8-out analog (with optional D/A card), 2 ch AES digital out, wordclock i/o, UV22HR dither, SoftLimit. The 2 AMBus slots accept optional cards to add more i/o formats: ADAT, TDIF, Pro Tools, Pro Tools HD, SDIF-II, SSL or FiberDX.