Wow. The experts seem to have their panties in a bunch. Grow up! How would I know how to value your ‘expert knowledge’ if you act like insulant adolescents?
To answer your question, I would just enjoy the new dac for a while. Get to know the new sound before you decide to change anything again. The dac is far more deciding for the sound than the files you feed it.
Now I don’t mean high res vs cd quality but how you transfer a file. With usb you don’t feed a stream but you transfer a file to the buffer in the dac. Yes, you can get a bit of noise over a cable just by connecting it. It’s up to the dac to galvanically isolate that.
I only have an RS250 feeding usb into a DDC which then feeds iis into a Laiv Harmony. In all honesty, I couldn’t tell any difference inserting the DDC. The upgraded dac however made a huge difference.
My wisdom of over 40 years of upgrading: give it time and enjoy what you have.