Thanks Dmitri
Everson I'm sorry if I advised you to increase the xTalk value, I thought it might help to reduce crosstalk from the piezo's .
For the resistence i would like to suggest you to set the megadrum to default values, go to snare channel and hitting hard the pad , rotate the trimpot to reduce the signal from piezo and and read the Highlvl on megadrum, when it's cold use a Multimiter to see the value of trimpot and replace it with a resistor .
I have a good dynamic range with 650Highlvl and 10k resistor placed is series on positive piezo wire