Well, I don't think ASIO Proxy is obsolete.
Heh, I used the word "obsolete" in the meaning "no longer produced", but I'm anyway aware that my English is far from perfect.
I am using it with a genric es9018s DAC now (with the Amanero USB receiver) and it is working fine (with FB2K version 1.3.15).
For some reason, the DSD Transcoder did not work for me either. I downloaded and installed it without problem but just cannot select it in the menu during set up. May be it was something I did wrong but I did not explore further. Similarly, I have installed the DSD Processor plugin and did not encounter any error in setting up. But I do not think it is working either. I do all the upsampling settings under ASIO Proxy 0.9.4 using the Amanero driver as the ASIO device.
Regards,
Anyway, if it works well for you I really see no reason why not to use it. But on the other hand, I also see no reason why not to use DoP instead of Native.