Many greatly exaggerate when they talk about the uneven frequency response. I measured a lot of HF heads, and everything exactly matches the passport data. If there is unevenness, then no more than 1 dB, and only in a small frequency band. At home, this unevenness cannot be seen. Personally, I could not identify such unevenness. I saw someone spreading a terrible picture with a lot of 8000 beringers, well, this is a pure lie, with such unevenness, even just in the recording it would be heard. Their campaign was dropped from a height, then they were allowed into the test)) The only thing we can assume is that in other parameters it can be worse than expensive analogues. Well, let's say, to remove impulses, or perhaps it is less thermally stable, etc.