In addition, I have the idling noise reduced by approximately 60% (compared to Logitech) - which in very quiet recordings as MP3 Books (zBSchlafzimmer), etc. gives a clear gain in quality.
Because I am a human being and not a gauge I can not say where that frequency or even the great quality is transmitted or is played to the sound transducers themselves definitely.
The fact is that it sounds better - easy, quick and painless. Logitech way - Philips 2500 ago - have not regretted the 5 purchases.
.... Will buy simple - do not doubt this time!