Thank you for your comments.
You have Vorzuge Duo. But that model is the amplifier Alo? The Alo Mk3 B+?
In low range which of the two will always acts amplifiers performance and versatility? If I understand correctly the Vorzuge has a selector that adjusts the low function. Crushed dial the bass increase. The Alo Mk3 B+ has a potentiometer that allows for a better adjustment. The question is: when you adjust the selector of the amplifier Vorzuge Duo bass increase dramatically ?(and therefore might be annoying ..)