Weiss prefers FireWire over USB for several reasons.
Similar to USB FireWire offers the asynchronous operating mode. Unlike USB, FireWire also offers isochronous mode that allows devices a dedicated amount of bandwidth. This insures the audio stream will keep flowing without interference from collisions or glitches.
As most Computer Audiophile readers knowUSB DACs work great as long as there are no other devices on the USB bus that interfere with the DAC i.e. the keyboard and trackpad on MacBook Pro models. USB also puts more load on the CPU. Fortunately for many computers this load is negligible when audio is streaming to an external DAC. FireWire does seem like the way to guarantee a smooth audio stream to the DAC, but it is not without its detractors.
Some in the industry preferUSB 1.1 because it allows a 24/96 audio stream without the need to install additional device drivers.
Traditionally FireWire also has more jitter thanUSB interfaces. To handle this Weiss uses the Jitter Elimination Technologies (JET) PLL in the Minerva. This features state of the art jitter rejection and extremely low intrinsic jitter levels. Much more information about all of this is available in the very detailed Minerva manual.
还有一段话,是高端usb dac厂家wavelenth audio提出的,也非常有意思:
The DAC has a single digital USB input (no SPDIF inputs). USB unlike SPDIF is bidirectional and therefore has error correction and buffering on both sides. This happens automatically so the data on the disk is identical to what is going out all the time. Also since this interface is asynchronous the clocking problems associated with SPDIF go away. What happens is... On power up of the computer the 2 devices negotiate services. In this case the Cosecant tells the computer it can do 16 bit audio at 32K, 44.1K and 48K. Since the USB receiver only has to handle these 3 frequencies, The clocking to the separate DAC IC has almost no jitter. SPDIF actually has to be synched to the exact frequency of the transport (i.e. if the transport is working at say 44.0896K instead of 44.1K the dac has to sync to that frequency). Therefore there is no interface jitter like you see in SPDIF. So using USB we have a zero error protocol to link the computer to the DAC and very low jitter what else..... All these USBD DACS are platform independent also OS independent. Any computer that has USB output will be able to hook up to the Cosecant without software drivers. Just select the Brick, Cosecant or Crimson for Audio Output in your system preferences or control panel and your done.