Neutral: More channels than before did not come into it.
Negative: the sidebands from transmitters that came in before cleanly separated, suddenly (eg when Germany radio to 97.6MHz in Frankfurt) disturbed.
Therefore, rather than an improvement in deterioration.
The function of the amplifier I have checked: a deduction of Klemme30 cable (red) led to deterioration. The amplifier thus has an impact, however, on my radio is not to the benefit.
Since I can not rule out that it helps other radios, 3 stars.