From the web site I linked too:
The Looks
See below the unfiltered output of a 1-bit sigma-delta DAC, respectively DSD/SACD:
This is supposed to be a sinewave.
Following is the output of a 3-bit (multilevel) sigma-delta DAC.
Well, now you can estimate, it wants to be a sinewave ;-)
And now, take a look at a good old 16-bit R2R DAC:
Don't be afraid, to relate what you see to what you expect to hear.
The key issue that I want to address here is
noise. A R2R DAC can convert noise-free, whereas any sigma-delta DAC relies on the noise in order to randomly shape the immense quantization error.
Even if the noise is technically specified to be outside the human listening range, and also specified to be easily filtered away, any real-world implementation of any sigma-delta DAC will tell your ears a different story.
And Soundwise ?
In science, the experiment decides if a theory is held valid or discarded.
This is of course difficult when a sound quality is subjectively assessed, as science only deals with instruments, as the experiment for being considered valid, must be repeated consistently.
This is the core of all arguments of the following type:
A: It is flawless and perfect in any scientific, engineering and mathematical way.
B: But it sounds so bad.
or the other way:
A: You cannot do that at all. It is totally wrong and you can measure numerous kinds of distortion.
B: Hey, now its just right. This is the way a saxophone sounds 
Subjective Evaluation
R2R/Multibit/Ladder DAC:
What I personally like with R2R converters, is their ability to reproduce a wide variety of timbres. A cymbal can really sound like a cymbal, not like crinkling a piece of paper. A piano can have body.
It is the richness and diversity of complex harmonic structures that a well done multibit or R2R DAC is able to produce, which can make it a very musical and real sounding device.
And this is the reason why I use R2R technology inside my
Attraction DAC and
Tera-Player!
Position of instruments is rock-stable.
Sound has balls, and at the same time precision. It can drive
If there is any sonic signature at all, it is one which could best be described as "chocolate-like".
Sigma-Delta DAC:
What I personally dislike with any sigma-delta DAC I have listened to up to now, is the lack of reproducing a voice's or instrument's timbre, and the lack of all other positive aspects of R2R DACs, as mentioned above.
Instead of being able to enjoy the richness and variety of different sounds, I have the impression that everything sounds the same, or has the same imprinted character, which could best be described as nervous fizzle.
There is no tone and no body. No balls, no precision, no transparency and no drive.
What is left is the annoying sonic signature, ranging from "acid to pink hiss".
The more levels or bit-resolution are introduced in a sigma-delta converter, the less annoying the sound becomes.
The worst sound can be achieved with 1-bit modulators, as found in DSD, respectively SACD.
Apart from SACD being a complete waste of storage space, the achieved resolution is low, and the musical presentation ranges from "very lame without detail and drive" to "more detail but very acid".
PS: For being fair, some people relate what I call "nervous fizzle" to "very wide and open soundstage". I consider this an issue of listening level, or perhaps - in better words: personal preference. To me, the realness of a musical presentation is to a large part determined by correct timbre (tone) of instruments and voices.
PPS: Recently I was able to audition a very expensive and high-performance CD-player that runs on 4x AD1955 sigma-delta converters per channel. Although that was definitely the best and smoothest sigma-delta presentation I had heard by then, I was not completely satisfied. One or two octaves were underrepresented in the lower end, soundstage was quite narrow, although none of the typical switching noise was apparent. But subjectively the worst and most consistent problem was the inability to play different timbres. Every instrument sounded the same, as if covered with a gloss of plastic, not PVC but a higher quality plastic...
PPPS: And this is the reason why I completely avoid Sigma-Delta technology in any and all of my audio products.
