How is the Pi currently connected to the DAC? Optical? Coax? (Make sure you DAC is capable of receiving 192kHz over optical – not all DACs are).
Do you use the Hifiberry image? You may want to try DietPi and install Roon Bridge from the software menu. That way you can use you DAC via coax/optical – or (if you change your soundcard settings) via USB.