Here is my two cents worth. I had several ~$1K DAC and they were all indistinguishable from one another: Jolida, Channel Islands Audio, Denafrips Ares, Schitt Gungnir, and couple more that I have forgotten. I upgraded to a used Ayre QB-9 and was absolutely astonished with the SQ improvement immediately! I then upgraded to an Ayre Codex, with a similar sound, which allows me to stream my Oppo through the DAC. It is fantastic for a very reasonable price.
I visited a friend of mine in Italy his summer who used an upgraded Denafrips Terminator and I was absolutely blown away with the sound of his system with his Buchardt S400 SE monitors. It is among the finest, most natural sound systems I I have ever hear, regardless of price.
He has since upgraded to a Chord Hugo (~$10K) and is ecstatic with the improvement in SQ. He is adding the Chord M-Scaler device to the DAC (~$4K) and expects solid SQ improvement. I do not doubt the dual devices are in the realm of the uber-expensive DCS multi-component DAC system.
I know that there are some sub-$2K DACs around that get rave reviews, Holo is one of them and Audio Mirror is another. Worth a listen, for sure.
My take is that more or less you need to spend ~$2K to play in the big leagues of DAC's. The Ayre Codex and Schitt Yggy will get your most of the way there.
