Are all asynchronous USB inputs similar?

I would expect that different asynchronous USB interfaces will generally differ significantly in terms of how much noise and jitter (timing fluctuation) ends up being present on the clock (the timing signal) that is provided to the D/A converter chip itself. That in turn can be expected to have significant sonic consequences.

Even if the electrical designs of two asynchronous USB interfaces were identical (and in general they won't be), just differences in mechanical layout, signal routing, grounding, power distribution, etc., would be likely to result in significantly different amounts of jitter.

Regards,
-- Al

Al is correct. Each design is different. Its not just jitter either. The output driver impedance matching and voltage is critical too.

Steve N.
Empirical Audio

The one thing that they all have in common is the poor sound quality. USB is for connecting your printer, not your DAC. If you notice the new era of servers, they have abandoned USB due to its poor sound quality. It was originally used as people just did not want to open their computers, so, since USB is like a belly button (everybody has one), thats what they used. It was a convenience thing and never meant for high end applications. This just snow balled with the manufacturers (it was easy and CHEAP)as they all embraced the interface. You can now see how the new designs are not using USB due to a myriad of reasons, one being the natively horrible jitter factor. You need to spend alot of money just to (try) to tame USB jitter.

Dont believe everything you read. One thing that all PCI interfaces have in common is poor sound quality. The power and ground planes inside a PC are just too noisy to achieve a low-jitter master clock. Best to get this outside the computer and on its own low-noise power supply as in Async USB. Computers are built as cheaply as possible, including the PCI infrastructure. They are barely good enough to operate, but not good enough to support a low-jitter clock. I know because I worked as a designer and design manager at Intel corp. for more than 17 years and at times in the platform group.

The right USB interface on the right power system will always beat a PCI card inside a computer, as well as 99% of CD transports.

Many more rooms at shows get awards with USB interfaces that those with PCI interfaces.

Steve N.
Empirical Audio

Tell that to baetis. Just cause there was USB at more rooms is a silly response. The world is flat again? USB is done. Thank the lord. Puters are built cheap but that ol USB output is made of gold. Ithink the Brooklyn bridge is still for sale.