I don't have any other USB-C to USB-B cables to try it with, Jr. Radnev. I bought this one brand new (of very decent quality) recently and specifically for this usage. The existing cable works perfectly with a Shanling M0 ---> DAC-2: any/all formats & any/all sample rates. I think that proves the cable is not the issue. Hope this also answers Kai's most recent question.
I am extremely upset and angry with Xduoo. Before posting here, I sent them an e-mail about a week ago describing the issue that has apparently been ignored. I wasn't sure if the problem was with Xduoo (works with everything else except ADI) or if the problem was with ADI (works with everything else except Xduoo). At the very least I thought I would get a response from Xduoo containing technical data that I could provide here to ADI.
It makes no sense to me that a device with no output stages, op-amps, or DAC decoding capabilities -- a device specifically made exactly for this sort of usage -- and more than 2.5 times the cost of an average standalone DAP -- could ship with this type of compatability issue with what I hoped to be the last DAC (ADI) I needed for the forseeable future.
Matthias, I really hope there is someting ADI can do to make the device more compatible with other class-compliant varieties because for something so versatile and with so much R&D put into it, it deserves maximum compatibilty. Customers generally have no way to know if their device will be compatible until something like this happens, and it's a most unwelcome surprise. I know this may not be easily solved, but if your team can slowly work on it that would mean a lot to me. I don't care if it's included in a firmware update 6 months from now, if that's how long it takes to do it comfortably. I'd rather get these compatible in time vs. not at all.
I'm sorry I don't have any more data about the situation. I did reflash the ADI firmware to see if that made a difference, and it did not. For the time being, I will have to settle for not being able to use the X10-Tii via USB-C, although this restricts me from DSD128 and higher. I only have a few albums at this level anyway, but it's the idea that bothers me most.
I just don't see any good reason for it not to work, or be made to work. Thank You All.
Edited to Add: What continues to remain most bizarre about this situatiuon is that the X10-Tii via USB-C DOES WORK with DSD (64 & 128), just not PCM. It's as if there's some little oversight somewhere that just needs addressing as it isn't a complete failure of compatibility. For me however, with 90% of my library being PCM, it feels like one. Matthias, again, I appreciate your responses and theoretical insight into the situation. Please don't take my response as disrespectful. I do not approach your technical knowledge. To drop about $1,500 USD on two devices, with the intent they will play well together and seeing no reason for them not to, but end up being incompatible at USB level is hard to swallow.