Schiit Yggdrasil -- 21 bit?


Schiit says that Yggdrasil is a 21 bit DAC. But the DAC chips that they put in the device ( Analog Devices AD5791BRUZ, 2 per channel) are 20 bit with the error of plus-minus 0.5 LSB.

How can the DAC be 21 bit if the chips are 20 bit? Using two chips per channel does reduce the RMS voltage of the noise by  a square root of 2. But how can you get to 21 bit from there?

Can someone please explain.
defiantboomerang
"Nothing comes close."
Implicit: "...because, I’ve heard ALL the others and speak from first hand experience. "

"All perceived differences are just due to placebo."
Does that apply to the Benchmark DAC3 as well?
@defiantboomerang

I had given the Benchmark DAC 3 serious consideration. I talked at length with one of their sales rep, and I very much liked the fact that he spent the time with me. Something Schiit really doesn't do.

If I recall (and this was months ago so I'm going on memory only), for one thing the DAC 3 uses a Sabre chip 9028 whereas my Oppo uses the 9038. Granted, we all know there is more to the sound than *just* the chip (i.e. analog stage, etc.). Regardless, I just couldn't get past the fact that the Sabre chip in the Benchmark would sound like my Oppo, which uses an even more advanced chip.

Further, the DAC 3 has many "cousin" configurations in their lineup, neither of which zeroed in on the specific (and only specific) functions I was seeking - namely bit perfect PCM conversion. I couldn't care less about the headphone amp, home theater bypass and other features in the DAC 3 that I don't need/want. And because the Benchmark isn't really any less expensive than the Yggy,  it seems to me the cost is spread all that much thinner across all of its functions. So it's PCM specific abilities should be inferior to the Yggdrasil, because the Yggy's design focus is just PCM.

Unfortunately I had no way of listening to either one prior to purchasing, so the return policy of each was also something I considered.

Still, I think I made the wiser choice in my particular case to go with the Yggy.
@ghosthouse

"Nothing comes close."
Implicit: "...because, I’ve heard ALL the others and speak from first hand experience. "

No, nothing comes close to their technological expertise. DAC3 measures better than anything out there -- hence, nothing comes close.

"All perceived differences are just due to placebo."
Does that apply to the Benchmark DAC3 as well?

Of course it does. Tough, I will buy it, when I save some more money. Not because I think it will sound better than what I have, but because I like technically advanced devices. As regards its sound, the placebo effect for subjectivist audiophiles should/will come from the reviews that praise it. For example, the Stereophile says that DAC3 delivers "ASTONISHING FIDELITY AND EMOTIONAL EXPRESSIVENESS".
@gdhal

Yes, DAC3 and Oppo will sound the same. Not because they use similar chips, but because all decent modern DACs sound the same.

I am glad that you are happy with your purchase.

As regards bit perfect PCM -- the DACs in the Yggy use R2R ladders, at least that is my understanding. The precision of such DACs is not infinite or bit-perfect, because you cannot make perfectly precise resistors. To make a 20 bit DAC work, the resistors have to be really precise -- the tolerances should be less than one in a million and stable when temperature changes, that is < 0.0001%. Those are some accurate resistors! And even with very accurate resistors, the steps between bits will not be uniform, so there will be no bit-perfect output. I wrote a simulation program to see how the accuracy of resistors affects the output of such DACs -- with less accurate resistors you might not even get monotonic output. That is, you go one bit up digitally, but the output voltage goes down. Strange, but true.

Now, don’t get me wrong, the chips in the Yggy are excellent. But if you read their application note, you will see that they deliver about 19 bits in real life. And that is just the chips, the whole device cannot do better than that. DAC3 has just been reviewed by JA in the Stereophile. It delivers about 21 bits of resolution. Not that one could hear the difference between 19 and 21 bits.
Yes, DAC3 and Oppo will sound the same. Not because they use similar chips, but because all decent modern DACs sound the same.


@defiantboomerang

Interesting insight on your part that you bring to this thread discussion. So if the DAC3 and Oppo will sound the same, please allow me to ask a question that essentially goes back to square one. In your opinion, why should someone who currently owns an Oppo (and is happy with sound) purchase or even consider purchasing a DAC3?