They both seem the same to me, but I haven’t given it much thought, as I believe they would be the same? But you need the dock really and a AudioQuest Cinnamon or Carbon USB cable. The second best is to use the dongle. I get my Carbon USB in about two weeks. But I can confirm the dock Is the best, the dongle is second best and the side miniUSB connection is the third best. Of course the side (third best) is a Sony USB included with a miniUSB and stabilizer plug with the Sony Walkman plug on the other end. They also include a regular USB cable with the amp.The dock has added circuits which is the understanding method which changes the sound.
So the promotional photographs all show the Walkman and TA in the third best configuration.
The Audioquest upgrade USB has been reported to really work wonders in this thread.
No one has reported the Diamond to be better than the Carbon though?
https://www.amazon.com/AudioQuest-Diamond-Cable-Type-75m/dp/B004LR7HP4
The Walkman input is miles better than SPDIF Toslink RCA into the TA from CD transport. Couldn’t tell you why? But I’ve checked it side by side.