I'm surprised that any USB to Firewire adapter works. The protocols are quite different. Even if you find one that works the performance is really going to suffer. You should look for a FireWire card for the computer, and add the interface the right way.

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs
-Chris