@dougms3
Thank you for testing as suggested. Now we've got a clue. Format
1411200 Hz not supported, it means that DSD Processor is trying to output DSD512 and Foobar returns error, which suggest that setup is done properly and SU-9 do not support this format.
It seems to be a true, as a maximum for SU-9 is DSD512.
I think you did already pickup my mistake, right?
No, there is no mistake. It is typical that when specsheet says a maximum supported is DSDxxx, but it is only valid for native DSD transfers. DoP transfers are typically limited to a half of a maximum speed, but they didn't say so and you are a victim of such marketing. In this case DSD256 DoP transfers is a maximum.
Replace all values on the DSD Processor settings page from DSD512 to DSD256, and I am sure, it will be working. If it doesn't, for testing try to play files you downloaded with DSD Processor disabled. DSD256 file should play, of course you should use the oputput
DSD:ASIO:USB DAC ASIO
A reason is that Foobar only support DSD PoP playback. To get a native DSD transfers you have to install on the Windows PC a proxy device driver. It is called DSD Transcoder. How to do that, it is covered on the Foobar for Dummies webpage. I will not try to help on this matter, as my experience with DSD Transcoder is negative. I had strange occasional behaviour. It is not worth efforts, trust me.
TL;DR, You are stuck with DSD256 or use a different player that can do a native DSD transfers.