AKM makes the best DACs

To simply say what others have said differently, your statement is tantamount to stating "The GE 9X jet engine makes the best jet plane". I try my best to resist the "what I have is best" tendency so often demonstrated on this Board and all audio boards but be that as it may, I will put my SW1X DAC IIIB up against any DAC in existence. It uses a very "outdated" Philips 1541 chipset. But the secret is in the sauce;

SW1X Audio Design™ DAC III Balanced Features:

• Pure & Elegant NOS (Non oversampling – zero digital domain filtering) Design
• Balanced (& Single Ended) Signal Output Transformer de-coupled Valve Output Stage Topology
• EL84 Power Output Tubes, Zero NFB, Class A, Valve Output Stage
• Passive I/V conversion via a specially selected resistor with the shortest signal path directly connected to the tube grid
• Dynamic Element Matching (DEM) of the TDA1541 powered by an asynchronous E180F Valve Clock powered by EAA91 Valve Rectified & Choke Filtered Power Supply
• Discrete Transistor, Shunt Voltage Regulated Low Voltage Power Supplies
• 5U4GYB/5R4GYB Directly Heated Valve rectified CLC (choke filtered) B+ Power Supply
• Digital Input supports up to 24Bit/96kHz S/PDIF Signal Input

• Specially Selected and Harmonically Matched Component & Material Quality
• SW1X Audio Design™ Copper wound Super HiB DC core Signal Output Transformers
• M6 grain orient EI core Mains Transformers & Chokes (HiB double C-core available as an option)
• Circuit is wired with Specially Selected copper conductors of various geometry (single strand or Litz)
• AN Copper Foil in Oil interstage signal de-coupling Capacitors
• Black Gate de-coupling Capacitors for TDA1541 DAC
• AB 2W non-magnetic Carbon film Resistors in selected places

Tube Compliment:  2 x EL84, 1 x 6N6P, 1 x 5U5GYB/5R4GYB, 1 x E180F, 1 x EAA91

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. 

@melm 

Great post. The main intent of my post is to point out that optimum DAC design is osteopathic and not allopathic. Treat the system and not the symptom. And I say this as a lawyer who sees only MD's as doctors.