@j_andrews Look for Amanero or XMOS usb board in dac, not aware of any other top flight usb implementation on dacs.
I had Singxer SU6 at one point, never even bothered listening to it as research and logic made it moot point to even bother. Added complexity, DDC do have issues, even the SU6 benefited from modifications and even more complexity. The other thing remaining in favor of using usb vs I2S was optimal usb implementation in both streamer and dac, point is stick with best ports on streamer and dac. Agree with Latik, the best streamers negate the need for add ons like DDC, they provide top flight rendering, DDC superfluous. In can see how DDC could better streamer with less than optimal rendering or streamer/dac mismatch with optimal ports. AES/EBU should also be considered a contender, although not much talked about, Antipodes claims this best output in K series streamers, came very close to purchasing. At some point I may get around to trying various JCAT and Pink Faun PCIe cards in my streamer, I2S and AES/EBU both available, along with the more usual usb and network cards.