I work with WAV every day.
What difference? Flac and Wav? If so, how did you test that hypothesis?
So hang on. If I understand you correctly. This product is being derided as a bad design by you, despite nearly every review and you can’t hear these appalling shortcomings?
I didn't say I can't hear it (I didn't try). I said most likely
you can't because instrumentation clearly shows the distortions. Yet you say it is clean as a whistle. Ergo, nothing is wrong with the instrumentation. It is just that when distortions get this small, almost every audiophile or pro audio gear fails to hear them.
Bottom line, your observations are consistent with the review. They do not in any way invalidate the measurements. Nor do they point to a broken device.
As for "every other review" this forum exist because those reviews can be trivially shown to be wrong. They are full of non-scientific, random subjective reviews that has been shown to be totally unreliable. That is on top of 99% of them being positive.
Here, we are about what we can prove, not what earns advertising dollars. Measurements are provable attributes of engineering and many times can indicate audible problems. If this is not your cup of tea, you will be disappointed and sour.
The hope is that you hang around here for a while, read what we discuss, the authoritative references we use to back our opinion, and provide a compass for future purchases that are based on sound audio science and engineering. And no, no amount of "working with .wav" would have taught you any of this.