I have neither Atmos nor DTS capable equiment, but when transferring SACD or Blu-ray into roon I’m getting Atmos and/or DTS files as well.
I’m not sure how the downsampling in roon works - would it be ‘enough’ to rip the Atmos content, and use that even if I only got DTS capable equipment at some point…?
How does everybody else do that?
Roon does not support the Atmos layer for playback as it cannot play it back, but it does give you a high bitrate multi channel embedded version.
I have ripped several dozen multi channel SACD and ATMOS Blue-Ray in various formats for putting into Roon and Plex server. I mostly play them back through Plex but I also have my DietPi Roon server connected to my LG C3 TV which is connected to a Sonos ARC, surrounds and Sub woofer and I can say from Roon that way it sounds pretty darned good. I generally prefer Plex but it depends how lazy I am feeling at the time.
Since Roon only supports up to 8ch PCM contents, once upon a time I rendered Atmos audio to 5.1.2 discrete wav or repack it to FLAC and let Roon play to 8ch DAC.
And I still do it that way. 
JCR