Yes, the USB input is asynchronous UAC2.
S/PDIF coax and USB will handle 44.1, 48, 88.2, 96, 176.4 and 192.
The S/PDIF optical input will just barely have enough bandwidth to handle 192. Not all sources will transmit 192 over optical, so it's more a case of what the source will transmit. The cable is also important here, since 192 over optical is right on the edge of what's doable a not so good cable can muck it up. (do NOT ask me for a list of cables that work, I do not have such a list)
I'm designing the USB input to handle 8 channels, but the hardware and firmware to couple multiple DAC boxes together will not be available at first, it's going to take some time to get that ready.
John S.