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
Yeah, the publication industry and a good deal of the industry have become so oddly slanted, its become the true impediment to high fidelity.

One example, and this has vastly greater importance than this bit depth discussion, is the  idiotic effusive behavior of the publishing community in regards to high resolution recordings and the primary driver of why high bit depth digital converters are sold for.

Lets take a modern multi-track recording that might be released and adervertised as high resolution, but in truth hardly qualifies. I run analysis of the files and find a single instrument being recorded above the standard RB 16/44, with the remainder showing no a single aspect of a high resolution recording. So out of this entire multi-track production, in instrument or sample was in HiRes. It gets mixed together, with all  the other tracks going through and up sampling and sold as high resolution recording. At best, is RB+ or 16/44+. In every rag, each and every month, every reviewer should be checking and reporting and being critical about the state of recorded music. All this gear and too many piss poor recordings.

Also, today we do have gear that can exceed the modern Red Book recording. But keep in mind that the vast majority of speakers and amplifiers couldn't cope on 20 bit recording at scale. Some can do over 19 bits worth, but it won't be composed doing so. Amps and pre are also under this limitation.

Now as for that Benchmark DAC3 HGC review, those are some excellent bench test results. It seems that ESS had improved upon some of their filtering as well as some other tweaks being added. While I could pick on some level of improvements from lesser DAC devices my own, or even something like this, at this level the differences between other high performance devices that measure properly are hardly audible. An engineer can modify the final output to their preferences, but that's a designer coloration. But my hats to Benchmark, this is an engineering marvel!

Amusing to read various reviews on the DAC with most reviewers stating they couldn't discern a difference between it and other competitors at near or well above its cost. Big old surprise right there!  
It's really striking when audiophiles ask engineers to tell them how good something sounds. I'd love Stereophile to put on their bench a Guarneri 
vs a Stradivarius. My next concert will be incomplete without precise measurements.
I'd love Stereophile to put on their bench a Guarneri
vs a Stradivarius.
Probably could, if they plugged in.

Cheers George  
@mmeysarosh

Good points about performance measurements. I was surprised about the DAC3. I didn’t expect to hear a difference but I believe I could. It wasnt a difference in sound but more akin to better blacks on a TV - the sound popped out of the background in more detail. Not sure I could detect this in blind A and B tests - definitely subtle. I believe the performance in many of the latest DACs is on a similar excellent par. My speakers have THD distortion below -65 dB across the spectrum and also can play cleanly up to about 120 dB SPL which helps to discern such small improvements at low signal levels.