DSD forced upsampling question

Why is the DSD 256, 512 Forced Upsampling in the Audio Filters options tab grayed out? Does this limitation come from either of the following items in my system: Dac - Twisted Pear Audio, Usb to spdif converter card, Macpro notebook, or any other issue with the A+ setup options. Question is posted to find which one to investigate first.

And which DSD filter option is recommended, i.e., A, B and which order? Where could I get descriptions of each one characteritics? Thanks!

You won’t be able to do DSD512 with Mac. It depends on your DAC whether you can do DSD256.

For DSD modulators, probably B7, B8, or C would be the best choices.

If you’re dac supports 512 then the highest you’ll manage direct via a Mac is 256 as it will be doing dop. Dop uses double the bandwidth so you halve your max upscale. This is because there are no asio drivers for mac to do native conversion.

Route I took was to use a transport. I have a Sonore Ultrarendu taking Flac from my Diskstation and outputting to my Brooklyn Dac+. My Mac mini is upscaling via Audirvana to native dsd256 which is the highest the Brooklyn can go. My other dac (SMSL M9) will do 512.

Microrendu or Usbridge are other alternatives.

I have newly discovered the benefits of upsampling in Audirvana to DSD. I am streaming to a PS Audio DAC. I came across some performance figures put out a few years back by mansr, the author of the DSD modulators on another forum at https://audiophilestyle.com/forums/topic/27759-audirvana-plus-251-with-pcm-gtdsd-conversion/page/47/#comments. But these only cover the A and B filters. At the time, it seems that the C filter was thought to have been the same as the B 7th order filter. But I seem to hear differences between them. Am I just imagining this? Are there any performance figures available for the C filter that may show some difference? I assume there must be some difference in the implementation or there wouldn’t be a C filter option. Thanks!