Consider a device constructed from a low-noise high-Q 1kHz sinusoidal oscillator. The device takes a PCM input which it rectifies and LP filters to well below 1kHz, which is then used to set the amplitude of the generated 1kHz tone. This device would score very well on the DAC SINAD test despite the fact that it's not a DAC at all! You need at least a frequency response test and probably also the IM distortion test to show that a device is even a DAC.
We are clearly simplifying...and the tests done by our host include far more than a simple 1kHz test signal. When multitone, and all the rest of the measurements are included, the device is characterized well enough to make a transparent/non-transparent judgment. At the end of the day, until someone can show that this approach leaves enough on the table for clear and consistently repeatable identification or preference, it seems like it is sufficient, despite all the calls to find what we must be missing.
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