No, you are quite correct. With USB, all modern desktop DACs are clock masters and just request data from the host at their needed rate. And they can use a local high quality clock circuit for this. As opposed to coax/optical where the clock has to be recovered from the raw signal, with the methods for this being considered mature, though. That is not to say that problematic designs cannot exist, of course. Specific testing and debugging for this is required to see what's really going on under the hood when a Topping DAC fails to connect to a CD player.Hmm, it sounds like a lot of additional work is required to recover a signal from coax/toslink as opposed to USB (or maybe I'm misunderstanding).