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

@rsjaurr
One thing you said rings true for me and makes me reconsider my goals:

I highly doubt if any other DAC can give you better sound in an almost similar price range.

I am starting to wonder whether buying something else will only show me how good I have it currently with the Adagio. I want to stay with R2R so the Holo May KTE and the Mystique will stay on my list of DACs to satisfy my curiosity, and of course I would jump at a good deal on a used Totaldac.

However, another consideration is the specific implementation. When I read about people who say so and so DAC is better than another DAC, I wonder about their implementation. For example, the USB input and RCA outputs on the Adagio/Pavane are not supposed to sound as good as the I2S input and balanced outputs (both of which I use). The rest of my digital chain (Ethernet/Bonn switch/TP Link Fiber Optic converters/Ethernet into the DX/Ethernet into the Metrum Ambre/I2S into the Adagio/then balanced outputs) should optimize the sound of the Adagio.

Regarding preamps, I have owned the Lamm LL2 Deluxe, NAT Symetrical, CAT Ultimate MkII, and other pretty good tubed linestages, and none of those gave me as much satisfaction as my current SMc preamp. Thank you for the reminder that the Adagio is a pretty good DAC.

Adagio/Pavane is a beautiful sounding DAC and it's a keeper for a longer time. I heard Cees is developing a new DAC for about 10K and we also know that his DACs are modular.
You must have heard about their plan of upgrading Jade/Onyx to the levels of Adagio/Pavane. So Cees might think of upgrading the current Adagio/Pavane to the next level by changing the module. Wishful thinking but you never know.

The addition of Marantz SA10 a few months back made me realize that something is wrong with the USB input of my Adagio. So I bought a used Gustard U12 to use the AES input of Adagio. Results were very surprising honestly. So now I plan to add Denafrips GAIA (or at least Hermes) and install the i2s module in Adagio to use i2s out of GAIA. 

Earlier I was thinking of buying either of Aurender N10, SOtM trifecta, Lumin U1, or dCS network bridge. So just a trial of U12 has saved me more than $4000.

In my world, I2S out of the Ambre has been the best sounding input into the Adagio, followed by AES/EBU, with S/PDIF and USB being less desirable. To my ears, using Ethernet from the Roon Core into the Endpoint (i.e., the Metrum Ambre), and having no USB interfaces in the signal chain has been a sonic improvement - and yes, I did try some pretty good cables (i.e., Totaldac and Curious) as well as all the usual suspects in the world of small box USB do-dads.

Since I also own a Jade, I did pre register for the DAC3 upgrade but wasn’t clear whether that upgrade also affected the Adagio/Pavane, although I let them know I own both.

I have no experience with the Gustard U12 but I see it is a USB (input) converter so I assume your source is a computer. If you are able to use a direct Ethernet connection, the Ambre works great and was sonically comparable when I owned both it and the SOtM Ultra trifecta (slight differences but both units sounded good). The I2S output connector from the Gustard uses HDMI so you will need to adapt that to RJ45. Hopefully the Gustard or Metrum folks can help you with the wiring. Here is a review of the Gustard U12 with measurements, in case you have not seen it.  BTW, if you heard positive improvements by using the Gustard U12, the Denafrips GAIA should perform very well for you since it looks like a serious piece of gear and quite versitile.

Amber seems an obvious choice but I do not want Roon. One of my friends is using modded Amber with great success.

I have built a computer audio transport in a Streacom FC10 chassis, powered by HDPlex200 LPS and OS is APL4. I have installed Cantata and use window10 to remotely control my transport. This works very well for me. But the problem is the USB input of Adagio which I want to avoid.

U12 is only temporary till better quality GAIA or something similar is added. U16 has good reviews but GAIA has better specs on paper. SOtM is out due to the hassle of multiple boxes and their power supplies. Audio-gd DI-20HE is also out because of its i2s connector being RJ45. 

If you can live with the boxes, you can sometimes find all three SOtM Ultra units (including the switching PS, which is pretty good) being sold at a good price.   They did sound good but in a full-bodied sort of way with maybe a smidgen less resolution than from the Ambre.  Both were grainless and musical.  It was really a pretty close comparison with the Ambre, and I owned both units at the same time.  The Ambre was just a little more dynamic and hard-hitting and the SOtM a touch richer sounding. However, they were so close I chose to keep the Ambre because it is only one box and because it dropped Roon less often (from seldom for the SOtM unit to pretty much never for the Ambre) and was easier to restart after powering down.  The GAIA looks like a nice unit.

BTW, how did your friend modify the Ambre and in what ways did the modification make the Ambre sound better, if you can share?