For years, have been very happy using an I2S Bus interface to DAC's like the original Audio Alchemy DDEV3 and Perpetual Technologies P3A DAC units. Both had large sound improvements over the coaxial S/PDIF.
I have seen the PS Audio I2S Bus over HDMI, but that will not work with the older devices, and most modern DAC's have the original style I2S Bus interface on the chip.
The Raspberry Pi style DAC HAT's use the I2S Bus interface on the GPIO to drive DAC's directly. You use a dedicated music OS like Volumio or Moode to do the playback as the RPi4 has some dropout problems when running full Raspbian Buster OS as I have tried. Not big on Linux, so time to try something else.
It is time to try this with a SBC that runs Windows 10 64bit OS and see what happens with I2S Bus as there are now GPIO available on some of them. A few things need to be added, but that is very straight forward these days to have high quality audio.
With Windows 10 music players like Foobar2000, JRiver MC27 work well so those will be the starting points. Both support things like room correction, headphone correction and room measurements. Other programs like Room EQ Wizard will also run and can be used. For recording from analog sources, Audacity has been very good as well.
Hardware is here for trials, so will post as testing begins in this thread.