I think we have a direct opponent to the Vorzüge Duo, as long as you don't touch the two freq options :
Gain 1, treble 1, bass 3, freq L : clean and unbeatable deep bass
Treble 2 bass 1 freq L: classical music comes to it's true beauty ! Strings are violently beautiful, same as voices...
Wagner's ouvertures are impressive, feeling like rubbing myself to the orchestra...love it!