I'm an old fart too, try Gordons explanation from his website;
http://www.usbdacs.com/Concept/Concept.html
Gordon wrote Streamlength - the code for Wavelength's asynchronous USB. It's also the code that runs the Ayre's QB-9 Dac and the Halide Design, Bridge USB to SPDIF Converter, I'm not sure who else if anyone, he has licensed it to.
My basic understanding is you are slaving the computer to the DAC. A firewire interface can operate in a similar manner.
If you plan on using a computer as a transport, it's worth looking into - mine sounds great to me.
Edited by MikeLa - 7/12/10 at 6:54pm