There’s some really affordable Roon “endpoints” to allow this. Here is a HiFiBerry DAC+ Pro that I bought my dad to use with his 1970’s Sansui Integrated Amp (here it’s shown running PiCorePlayer but it’s now running Ropieee with Roon’s RAAT):
HiFiBerry also make the Digi+ Pro, with Toslink and Digital Coax outputs, which I also got my dad to use with his Denon 4520 Receiver (running Ropieee Touchscreen):
These are really small and low powered Roon endpoints, out of sight if you want them to be.
I’m using a fancier and pricier endpoint at my own place but everytime I visit the old man, I’m blown away by the performance of those affordable endoints and DACs. They perform way way way above what their prices suggest. In fact, I’d probably fail a blind test of the Digi+ Pro against my much pricier endpoint, with my DAC