The Piccolo is "one way" device. It is not translating your Decware settings to its input. So the right way to use the Piccolo and Decware together is using impedance selector of Piccolo and set the Decware's to 47k.
I think if you have only MC (low) cartridge - you may change the impedance resistors in Piccolo just to cover the useful range (originally the resistors range is universal - from MC-low to MM).