My set up is roon core on Windows to a cubox RAAT device and via USB to my non MQA ready DAC.
This signal path tells me, I really do get a 24bit stream from Tidal, that is converted to flac and sent after upsampling to my DAC.
I understood, that is not possible yet. So far roon can only send unchanged mqa to the DAC.
Thanks for anybody who can update my understanding!
All Tidal MQA is 24 bit. That is part of the MQA encoding process.
AJ
That is clear, but I wondered whether I can really play it via roon to a non mqa DAC.
I thought in this case tidal will only stream the regular 16bit flac.
This would be a real nice surprise to me 
Yes You can stream the 24 bit file Tidal file using Roon to a non-MQA DAC. You will not get any of the MQA decoding of course but there is still an improvement in many cases over the same 16 bit non-MQA file.
This is not well documented in marketing materials.
Tidal MQA music is 24-bit before any MQA decoding takes place. Some Tidal clients / devices including Roon, Lumin, Esoteric N-05, and TEAC NR-7CD, etc. can get 24-bit streams from Tidal even before they achieve MQA certification. To the best of my knowledge, some popular Tidal client software (not referring to Tidal official apps), and some devices such as Linn, is not getting the 24-bit version and they get the 16-bit version only at the time of this post, even if the user chooses a Tidal Masters album to stream.
Thanks to all for the excellent explanations
Is there some setting in Roon to enable 24 bit in Tidal. I also don’t have a MQA DAC, but I always get 16 bit in Tidal.
Well, to get the MQA file you need to go to settings / streaming and enable HIFI/Master, which requires that you have the CD quality subscription level. And then you need to play an MQA file, not all files are 24 bit, just some of them.
