The short answer is "no." And the reason is that, unlike USB, Firewire computer interfaces all need custom drivers written for them. If you buy a Firewire DAC or Firewire - SPDIF converter, you will need to install drivers on your computer and probably futz with them a bit. It's not necessarily hard, but USB interfaces require nothing of the sort.
If you want to go Firewire, I would go with a true Firewire DAC, such as the Weiss DAC2 or their new DAC202, rather than a Firewire-SPDIF converter into another DAC. The latter approach can yield good results, but you'll still have to deal with drivers and you are adding another clock into the chain. In my experience, you would do just as well as a Firewire - SPDIF converter by going with a good USB-SPIDF converter (ART, Bel Canto, Empirical Audio, Wavelength) or, better still, a good USB DAC, such as the Ayre or one of the Wavelegths.
