You need a real high end streamer. Your other equipment is excellent. I used to run a Moon 650 DAC / CD player. I streamed from PCs and MACs for years to get nowhere near CD quality until I bought a high quality streamer.
My first was a Auralic Aries G2. But I recommend an Aurender. I would recommend an Aurender streamer of comparable or greater value to your DAC. So my first choice would be a Aurender W20SE or if you want to conserve money an N20 (a compromise). But the Moon 780 is very revealing… which is why your streaming does not sound great. You have a $500 player attached to a $17K DAC. Your DAC deserves a W20SE.