DAC Choices - $5,000 to $7,000

What are the current top DAC choices in the approximately $5-$7K price range (new or used) that I should look at as possible upgrades to my current Metrum Adagio?  Having an on-board volume control is not a factor as I can operate my system either way.   If I wanted to spend more I would look at Totaldac, Rockna Wavedream Signature, or one of the other top-end contenders, but I selected the price range to achieve a sound quality that is consistent with the rest of my system and because I don't want to spend more due to the still evolving nature of digital technology.  I do like the more natural sound (to my ears) of NOS R2R DACs.  So far, I have considered the three below, but none seem to be a slam-dunk upgrade from the Adagio, which still sounds pretty good in my system.  The decision is complicated by having to "buy to try" so that I can hear one in my system.  Maybe now is not the time for an upgrade.  Any thoughts?

• Denafrips Terminator w/DSP board - Reportedly has the full body/dense tone type of sound I like, but also has a high'ish output impedance 
• Holo May KTE - Reportedly measures great for an R2R DAC and has strong reviews 
• Rockna Wavelight - Some reviewers like it but others put it in the middle of the pack for the price