So it is basically an signal converter (mostly resides in the DAC) that converts the the data stream into SPDIF signal then output it to the digital-out. In theory, digital is digital - unless there is noise / error introduced in the process of conversion or transmission (i.e. jitter), then SPDIF from X3 should be identical to that of, said, QA350. To get accurate digital data from one device to another (i.e. X3 to an external DAC), they need to sync their clock (*working at the same pace). The clock data is encoded inside the SPDIF signal so the receiving end can use that to sync its internal clock.. However, if say the data is corrupted at the first place (i.e. a bad cable or a bad clock from the source), then error will be received at the other end. The receiving end won't know it is good or bad. The pro about asynchronous USB is that allow the receiver to go back and check the clock on the source to ensure the received data is in-sync (that's the jitter reducing part). However it is not to say S/PDIF must be inherently bad with jitter. A well implemented system can still achieve a very low jitter with S/PDIF, at least not to a level that can be detected by human hearing. Asynchronous USB greatly reduces the possibility of jitter, but it doesn't mean it must be there in the first place.
I would love to NOT have to buy a CLAS - my wallet concurs.
