I have recently made this kind of switch, but I also added a new component that makes a big difference.
I was using a Roon ROCK NUC, through an EtherRegen to a Bryston BDP-2 streamer and then via AES to my Terminator DAC. I tried connecting the NUC directly to the DAC via a high quality USB (AQ Diamond) and I thought the Bryston sounded a bit better (but it wasn't dramatic).
This past week, I received a Denafrips Gaia DDC. I removed the Bryston from the system and connected the NUC directly to the Gaia using the USB cable. Initially, I had the Gaia connected to the DAC using the same AES cable. This was somewhat better than using the Bryston, but wasn't dramatic.
Then I hooked the Gaia to the Terminator DAC using a cheap HDMI i2s cable. This improved the sound quality significantly, even though the HDMI cable was less than 1/10th the cost of the AES cable. I've got a high quality i2s cable on order, but even with the cheap cable, the Gaia/Terminator combo connected to the NUC via USB was a significant improvement over using the ethernet streamer.
The Gaia costs about $1700. The Bryston streamer I was using retailed for almost twice this cost. It's no longer a current model, but the BDP-3 that replaces it (and has the same digital audio output circuitry) retails for $4100. So if you are looking for something to use between your NUC and DAC (no matter what DAC you are connecting), and don't need to have these connected over ethernet, I'd recommend taking a look at the Denafrips Gaia (or their lower priced DDCs).