No, this is incorrect. There are two stages to “unfolding” MQA. First decoding, then rendering. Roon and some DACs perform the first step. So, for you MQA 192 kHz file this starts as a 48 kHz container that is unfolded to 96 kHz. This is what Roon sends to your DAC via S/PDIF (coaxial) connection.
Then the MQA enabled DAC does the second stage. This is called rendering and upsamples the 96 kHz to 192 kHz.
In Roon MQA settings describes the DACs capabilities. Is it a decoder only, renderer only, both or no MQA capability. In your situation, renderer is probably the best setting, i.e. let Roon perform the first stage.
Thanks to every one for their inputs - Allo suggested a driver update- but still no change .
So have concluded that the Onkyo tx 8270 digital inputs are constrained to 96khz( as advised by some of you) . I did purchase a spdif to hdmi converter - but that did not work - Allo said they would come back to me with a hdmi solution but nothing as yet. So have decided to return the raspbery pi and allodigione back to Amazon.
For the moment happy to play via a Chromecast audio through a tosslink cable to my Onkyo optical in , can get Tidal 192khz files playing fine( Roon just rendering as advised by others) - have to accept all my NAS files have to be downsampled to 96khz where necessary ,
Have decided to wait to save some pennies and upgrade from my Onkyo TX 8270 to the new Onkyo TX 8390 ( comes out in March and is built Roon Ready)
So thanks for all your help
Derek