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
defiantboomerang
Whatever happened to understanding science and engineering instead of relying on subjective assessments of "sound quality".
The two are not mutually exclusive. In any event, this is a hobbyist’s group, not an engineering forum, so please don’t insist that contributors here refrain from sharing "subjective assessments" of sound quality.
@cleeds 

A hobbyist group is fine, nobody objects to that. But being a hobbyist does not mean that anything goes. In particular, sighted listening is useless to judge sound quality. Blind tests are a but better, but to seriously judge audio quality, one must measure.
defiantboomerang
A hobbyist group is fine, nobody objects to that.
Some here have objected - very loudly - and they have insisted on scientific data to accompany observations. That's just silly on a hobbyist site.

 But being a hobbyist does not mean that anything goes.
Of course. These forums have rules, as established by Audiogon. Those rules govern the site.

 In particular, sighted listening is useless to judge sound quality.
That's opinion stated as fact.

Blind tests are a but better, but to seriously judge audio quality, one must measure.
Surely measurements have their place. But most of the great audio designers insist that listening is also important. Listening and measuring are not mutually exclusive.

I suppose you’re overlooking that Atkinson NEVER played the Yggdrasil to hear what it actually sounded like.
Solid state used to have ’perfect measurements,’ but it sounded crappy. I just listen: and I hear (and play) instruments a LOT, so I don’t care what measurements say. My ear tells me what sounds closer to real. I’m surprised at the if-it-measures well- it’s-going-to-sound-like-real -ife. I’m hear to tell you it doesn’t. ( I now play piano, flute, harmonica). If you don’t here live music, you know less than you think you do. You’re unfamiliar with what it live (unamplified) music sounds like. People nowadays (and I suspect they’re younger) compare technology as a means of predicting how a component will sound, instead of realizing they really need to hear live music. When you hear it live and then hear it reproduced "perfect measurements" or not, you know what’s better. How many of you hear live, unamplified music often? I’d wager, not many. You can’t measure ambience or "air": you need to have sufficient experience with live music to know that. Sound like most people here haven’t ever been in a symphony hall. What nonsense to think measurements are dependable. Feh!