AKM makes the best DACs

And now for a controversial comment.😅 I think FPGA is basically a marketing tool used to differentiate some DACS from the rest of the field. I find it almost impossible to believe that it can be feasible for an ordinary audio electronics company to attempt to out-perform the decades of development into chips by companies like ESS, TI, Philips, AKM, Burr-Brown and others, not to mention the companies producing discrete R2R circuits. After all, FPGA chips are still just chips (and mostly D-S, I think). Yes, they may be altered, but for what? To correct mistakes? To bring them to where they should have been in the first place? Or to bring performance closer to that of conventional chips? Moreover, I find that within most FPGA DACs there is less by way of power supply, clocking, and/or quality analog section than in conventional chip based products at similar prices. Their margins are tremendous. I’ll cite the PS Audio DirectStream as but one example. There are many others.

I’m putting my flak jacket on.

Marketing or not, I would not know, but there is an interesting quote from the link provided bellow...

’’So does this mean anybody can design their own DAC’s using FPGAs? No I am afraid not. Creating the internal modules, getting them right, getting the DAC technology right, has taken me 30 years to do. This is not easy to do.’

https://www.the-ear.net/how-to/rob-watts-chord-mojo-tech

by the way, BB also produced R2R chips....for example many of their 1704 variants  were used in different players over the years

Funny [to me] that Chord gets mentioned because imho Chord is a company that in Ahab fashion focuses so much attention upon the DA chipset at the expense of many of the other things that matter like the input and output stages. A good DAC should be built like a hybrid of both a well engineered and premium parts-spec'd preamp and amp. And this is also why so many DAC's that John Atkinson proclaims to "measure at state of the art levels" sound boring. Again, from the SW1X website;

The other weakness is monotonous and predictable character, which true for all DAC chips. Those weaknesses are curable with high quality voltage regulation, rectification and careful SPDIF receiver IC tuning. Last but not least is the lack of energy and perceived dynamics. That issue is partly due to choice of materials and components, I/V conversion technique and the choice of an output stage. The later part is plagued by impedance mismatch in almost all mainstream designs with a few exceptions.

The issue of impedance mismatch is critical in 2 places of a DAC design: A) Between the current out of DAC chip after the current to voltage (I/V or I/U) conversion and B) Between the first amplification output stage and the preamp/power amp input. Most common approach in the current out (best possible quality output of an R2R chip, which is impossible with Delta Sigma chips) DAC implementation is to use a passive shunt resistor as I/V converter. This approach works fine but has some drawbacks: the shunt resistor worsens the impedance mismatch further and it takes energy away, therefore some of the dynamics are irreversibly lost and all subsequent stage are lacking the drive. We, at SW1X Audio Design™ on the other hand, addressing the point A) by using a single transistor that does the job of I/V conversion, lowers the output impedance after the I/V stage (the DAC chip sees only 10 Ohm input impedance) and preserves the dynamics. Plus this approach allows us to use a simple but elegant class A, zero feedback valve output stage with low output impedance, which addresses impedance mismatch issue in the point B). On top of that the circuit remains elegant and simple and makes the music come alive with incredible dynamics and extreme analogue smoothness.

I did not set out to buy the DAC III Balanced. I ordered a DAC II Special from SW1X on a lark and with the benefit of the 30 day trial. I loved it. But then when I asked a question of him, Slawa Roschkow informed me that the DAC III Balanced is the "sweet spot" of his range of DAC's not because of being balanced in the sense that most of us think of the benefits of balanced topology but instead because the balanced design of his DAC insures internally matched impedances and further, the transformers utilized in conjunction with caps act like a power amp providing a robust output stage with better dynamics. Something is working. 

Notwithstanding the evident quality of the SW1X DAC (and it is a $13,000 DAC after all) the last place I would look for objective technical info is in on the PR pages of a manufacturer.  No one does that better, probably, than Chord's Rob Watts who is all over the internet in print and in video telling the world that the only way to do it right is the FPGA way he does it.  

But it is true, as was said, that when it comes to the other things, beyond chip set, the SW1X is a great example, and the Chord is wanting.  The DAVE (at $12,600), for example, uses an inexpensive to build switch mode power supply and two $1.50 TI chips at the center of the DAVE's analog section.  Another example of FPGA and not too much else.
 

No one will agree on best. I would say AKM dacs are the most ‘listenable” dacs on the market. Not the most in ultimate resolution but never any fatigue.