Two more items I want to touch on are the filtering and hardware components inside the Yggdrasil. Again, these items individually don't mean a thing (if the designer ain't got that swing). Schiit Audio uses its own closed-form filter that's hallmark is using the original samples, not throwing the original samples away while upsampling like most DACs. Good, bad, or indifferent, this is Schiit's way of filtering. Schiit says it doesn't do guess work because it keeps the original samples. On the CA forum, Mike Moffat
elaborated further by saying,
"It is a digital filter/sample rate converter designed to convert all audio to 352.8 or 384KHz sample rates so that it may drive our DACs. You get it uniquely from us; it is our filter. It took five people many years to design and perfect at the dawn of digital playback, way back in the early eighties. It keeps all original samples; those samples contain frequency and phase information which can be optimized not only in the time domain but in the frequency domain. We do precisely this; the mechanic is we add 7 new optimized samples between the original ones. All digital filters multiply the original audio signal by a series of coefficients which are calculated by a digital filter generator. Over the years, before Theta Digital was born (my original company), we developed this filter design/generator. The common digital filter method is a Parks-McClellan algorithm, which has been used in all of the older oversampling chipsets, and persists to this day as the input filter in most Delta-Sigma DACs. Why? I assume it is because it is royalty-free, and the algorithm is widely available as are digital filter software design packages to aid in a cookbook approach to the design. Now Parks McClellan an open form math solution, which means that the coefficient calculation is a series of approximations which always get halfway there. This of course, means it never completely solves. The worse news is that all original sample are lost, replaced by 8 new approximated ones. Further, the Parks McClellan optimization is based on the frequency domain only – flat frequency response, with the time (read spatial) domain ignored. Our filter is based upon closed form math – the coefficients are not approximations, the equations solve; the matrices invert and the math is done. The filter also optimizes the time domain."
In addition to Schiit's unique filter, the company uses unique hardware (at least in the audio world) in the Yggdrasil. Schiit uses four of the Analog Devices AD5791BRUZ DACs that are typically used in MRI imaging and military weapons. These DACs aren't trivial to implement in a digital to analog converter. I've heard many engineers in the industry suggest that the newest Sigma-Delta chips can be implemented much easier than a multibit design and that it doesn't take much to get a Sigma-Delta DAC up and running. It certainly takes quite a bit to get a Sigma-Delta to sound as good as possible, but nonetheless Schiit's selection of the AD5791 DAC has made its job significantly more difficult. In other words, not every engineer is capable of implementing the AD5791 in a great sounding audio component.