Tonight I listened to a classical masterpiece, "Edmond de Luca’s Conquerors of the ages" London Philharmonic; Linz Reinhard, conductor; Circa 1959. My favorite go to listening Lp. not only in terms of listening enjoyment but when it comes too high and low end sound tracks, some of the highest...and lowest sound passages I have ever heard on a recording. Since 20-20K Hz is for all terms considered to be the audible end posts for us humans, there are on particular tracks that I estimate come in at 30-18K Hz. The original album comes with a playbill that explains the composers intention tor each recording. A truly brilliant piece of work.