I havent seen any firewire transmitter yet, are you talking about a receiver like this:
http://www.engineeredaudio.com/products/aurius.html
http://www.engineeredaudio.com/products/aurius.html
USB Firewire Audio Transmitter/Receivers
Anyone know of any quality RF transmitter/receiver systems utilizing "Firewire" USB input (400 or 800), with the receiver's output via RCA outputs (or XLR)? I've seen several standard USB 2.0 versions, but would like to exploit 24/96 if available. Distance range >50 feet.