Computer output to DAC, which route?

Also, if you insist on using your computer directly as an audio source, do not use the onboard SPDIF output, or even a USB device. Use only a Firewire device!

Firewire supports isochronous data transfers - critical to a clocked data stream like SPDIF. USB does not support this!

Lupin - Async USB works great, and furthermore beats Firewire.

Read this:

....http://www.audiocircle.com/index.php?topic=105049.msg1159717#msg1159717...........

Firewire is dead!!

Async USB also beats Sonos, Squeezebox Touch, Soolos and other servers. Some servers now allow for async USB converters to be used with them, so this is a good development.

Steve N.
Empirical Audio

I know that you have the expertise, Steve, but I own both a firewire dac and asynchronous usb dacs. I'm surprised that you are so emphatic in your statement; given your past history (say on the "tubed" dac thread) I would have thought that you would have said that it depends which asynch usb and which firewire are being compared.

Richard - the Firewire that is available is outperformed by the best USB interfaces available. I'm not saying that it is not possible to build a Firewire just as good. It just does not exist.

I base my claim entirely on feedbacks from my customers, just look the post above. This customer was using my older Pace-Car technology USB interface instead of the Firewire input on his Weiss 202. Even Weiss went to a USB interface on their latest DAC.

There is somehow a perception that Firewire is superior and achieves better SQ. Simply not true.

If you have not heard a better USB interface than your Firewire, you have not heard the best USB interfaces.

Have you heard the latest Empirical Audio Off-Ramp 5, the Synergistic Research or the Diverter HR?

Steve N.
Empirical Audio

It is difficult to compare USB to Firewire since Firewire is expansion bus while USB is peripheral bus. Firewire speed is guaranted while USB speed is much lower than rated because it runs under protocol. 480Mb/s rated USB 2.0 runs at about half of this speed while Firewire 400 runs at full 400Mb/s (for the reason of guaranteed bandwidth is widely used in broadcasting industry). In addition Firewire does not engage main CPU having own processing unit with DMA ability. For that reason it was removed from Ipod since it posed security risk. Bringing device with Firewire to work might allow to bypass passwords (Direct Memory Access) and plant virus or spyware on the system or to steal company secrets. Big companies would most likely prohibit Ipod as security risk and that would be disaster for Apple. One thing that killed Firewire on (IBM) PC was greed. Apple charged $1 per port for royalties and that's a lot in very competitive business.

I'm not even sure how important speed is since 16/44.1 requires only 1.4Mb/s. Asynchronous operation might be a different story - don't know much about it.

One test for the future will be HDTV. Firewire 3200 could deliver (with 3% overhead) about 3100Mb/s bandwidth - not enough for 1920x1200 at 60Hz. What about Thunderbolt that has about twice the bandwidth of USB 3.0 and is likely to migrate to (IBM) PC ?