DSD256 is not accepted but downsized to DSD128

[ged_hickman1]

You can get 256 but the dac has to be capable of 768 pcm.
Here’s another thread with Macintosh DSD information

DSD256 format is unable be played on Roon via McIntosh C2600 [Answered]

The only way to get DSD256 to a capable McIntosh DAC is via a Windows computer and the McIntosh provided Windows ASIO driver. But be warned when using Native DSD mode with the McIntosh windows driver you will get pops on start and stop of playback with Roon and HQPlayer. McIntosh is aware of the issue and choses to do nothing about it as Native mode is only really specifically needed for DSD 256. DOP will work fine up to DSD128 as you have discovered. I was told via emails from McIntosh that…