How is it going? Just want to post an update, in case you or anyone else is interested. After sending messages back and forth to the manufacturer I think I managed to persuade them to release more stock of BT301 board so there is one seller on Aliexpress that is now selling it.
KT1025A chip the board is using is really a marvel of engineering. It has top quality DAC on board that has own analog ground. I compared the pcbs and it appears BT301 has this analog ground properly routed and as a result is less noisy than BT201 that has not.
I’m thinking of modifying BT201 board to see if it can be turned into BT301, I think it is possible, I also want to see if I can separate analog ground in the process that would make dealing with ground loops so much less of a pain.