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

Showing 2 responses by davide256

Awful lot of people obsessing here over measurements, one could almost mistake this for the Stereo Review website. Whatever happened to relying on A/B comparisons for what sounds better...
I've learned to put my hand firmly over my wallet when someone starts obsessing over measurements... usually what follows is a pitch for "mid-fi" gear where there are no A/B review defenders. I do hope that the original spirit of TAS remains with this site, seeking excellence of sound and ignoring the "midfi" spec game used to manipulate novices in their  audio purchases.