You should simply use DoP (i.e. not transcoding) for DSD64 and DSD128. Only if you have DSD256 files and DSD256 DoP does not work should you proceed with the following.
It is very likely you need to upgrade your Amanero firmware to 2006be11. It is not a trivial process, I’m not responsible if something goes wrong with it.
Old firmware definitely won’t work for Linux native DSD.