A lot of expensive DACS listed here and I have heard a few of them.
My next comment is for someone who wants to try something different and get sound like the $20kish DACs mentioned above.
Try a Schiit Singular DAC ($3500) + Schiit Valhalla 3 OTL/OCL preamp ($500) + iPhone Forkbeard app for volume.
I have not heard the Singular (or Byggy) DAC with a regular practical preamp, but it should be excellent. The Valhalla 3 is not a practical preamp. I now feel that the only way I want to hear tubes is via an OTL/OCL design. The Valhalla is the cheapest way to get an OTL/OCL otherwise, spend a lot more for an Allnic 15000 Signature OTL/OCL DAC + Allnic OTL/OCL preamp that is a better version of my Singular + Valhalla 3 + iPhone setup.
However, the best DAC I heard and one that has the cleanest and highest resolution of any DAC is the new imersiv D-1 at $12k. It sounds a lot different than the PlayBack Designs MPD-8 that I heard on a killer setup a few weeks ago.
I own the Singular and imersiv D-1 DACs. I can better the Singular (by a bit) but not the imersiv D-1.

