Okay, I get it,
it will be necessary to add a nano + connect the 5 wires, so I think to add mass and alim for the nano, resistances and capacitor.
The capacitor must be connected to VOL HIGH, is this the strongest point of the volume, or the middle point of the potentiometer. A priori since it is high it does not seem logical that it is the point where the sound signal is strongest of the potentiometer.
Is there an soft to load on the nano or does it serve a bit like a calculator?
Thank you for your help.