Firewire to SPDIF

I suspect that your question is mis-phrased, and you are referring to converting digital audio data carried via firewire or usb to analog audio, not to SPDIF. SPDIF is digital, and like firewire and usb is a means of transferring digital audio from a computer to a compatible dac or other device.

Also, many computers have SPDIF outputs, and if they do not, and it is a desktop computer, an inexpensive sound card with a SPDIF output can be easily added.

But to answer what I believe is your real question, whether or not usb can be counted on to consistently convey 24/96 digital audio to a dac, without intermittent breakup, it would be dependent on the computer. Quoting from myself in this recent thread:

It would be computer-dependent. USB relies significantly on processing by the cpu and its associated chipset on the motherboard. I would expect that a modern well-tuned computer with adequate memory will have no problems, but a computer which is bloated (as many are) with large numbers of useless background processes, and is configured with too little memory to support them optimally, and/or is running resource-hogging Vista, or is old and does not have typical contemporary computing horsepower, will have problems.

Firewire, in contrast, shifts most of the processing associated with the interface to the interface chip itself, and guarantees that the data rate will never fall below a certain amount (which was chosen to assure that the DV format (Digital Video, for which the data rate is much higher than for audio) could be transferred without interruption).

That thread does not address having the audio files on an external usb hard drive, which obviously would increase the possibility that problems could arise sending data to a dac via usb with a marginal computer (since the computer would have to simultaneously support inputting the data from one usb port and outputting it to another). Perhaps others will comment on whether they have done that successfully, including a description of their computer.

Hope that helps,
-- Al

The USB 2.0 can pass 24/96, but not USB 1.0. (USB 2.0 maxes out at 24/96). USB also uses the CPU which drains power usage (though there are some new USB utilazations by third party manufactuures which bypass the CPU issue). I have long been a proponent of the superiority of firewire over USB as respects PC Audio and from recent posts in other forums, more users are coming around. USB was never intended to pass audi. It was intended to daisey chain peripherals, ie mouse, keyboard, gamecontroler, printers, etc. I do agree that the new implementations of asychronious USB utilizations have narrowed, possibly eliminated the advantage, if processed (and installed) correctly. These are new developments and I have not had an opportunity to compare them. I am thinking that even with the new outboard USB advances, the datastream may still be better when handled by firewire as these new USB implementations are not able to change the issue of USB transmitting packets of info, rather than streams, as firewire does.

...you can (and I do) convert firewire to spdif for my dac (M Audio Firewire solo). Do a search on firewire vs usb for audio. Here is just one of the many links I have found:

http://forums.macrumors.com/showthread.php?t=526020

I haven't used the Echo.

Cerrot, My Benchmark DAC-1 instruction manual clearly stays that it utilizes USB 1.1 protocol, and is compatible with both USB 1.1 and USB 2.0 ports. USB 1.1 is the first widely used and bug fixed version of USB 1.0. It has a maximum data rate of 12Mbs (full speed), more than enough to pass 24/96 signal.

USB 1.1 still no where as fast as Firewire. USB still utilizes the CPU in your configuration and transmits packets, not data streams. Try firewire.