Yes, jitter is a very serious matter with computer audio. In fact, one interesting piece of information we found (though we did not confirm) is that computer manufacturers will ADD JITTER to their clocks for the purpose of spreading the energy across a wider bandwidth to pass emissions testing. Apparently the spike at the fundamental clock frequency was causing interference of some sort.
This is detrimental to audio, as most digital audio connoisseurs will attest to. In the simplest terms, jitter causes the digital audio converter to misfire. It’s like a bad timing system on a car's engine causing the spark plugs to fire when the pistons are not quite ready for it.
The Benchmark DAC1 and DAC1 USB are designed with a special clock recovery system that makes jitter irrelevant. The way it works, in simple terms, is - the DAC1 clock is not discretely attached to the signal clock, but instead monitors it and replicates it with an isolated clock which is extremely stable. This is described in more detail including performance curves in the manual (
http://www.benchmarkmedia.com/dac1/DAC1-Manual.pdf).
With this clocking system, the DAC1 will perform exactly the same no matter how much jitter is on the clock...quite literally. There aren't too many converters that can make that claim, but we encourage you to compare. It is for this reason that we tell our customers that it is not necessary to buy extremely expensive (<$100) digital cables. We've tested the DAC1 with cables of varying quality, and it made no difference whatsoever.
What does this all have to do with USB, you may be asking (please excuse my rambling...can you tell I'm not in marketing)? We haven't yet tested the jitter on USB interfaces, but from everything we know about computer hardware architecture, all signs point to it being a very serious problem.
USB protocol was not designed to stream data fluently and consistent; it was designed to transfer 'bursts' of data. This is the reason why audio drop out and 'ticks' are common complaints from users of USB audio devices. The DAC1 USB interface software and buffers were designed with this in mind; it 'monitors' the data flow to maintain a consistent and fluid audio stream.
The reason we announced this as our 'big news', is because this type of USB audio solution is the first of its kind with regard to the scope of the solution. It addresses more concerns then any interface of its kind. Even engineers at Microsoft and Apple were impressed!!