I am starting my own bass project (!) and I am trying to use a Bartolini 4.6 preamp for magnetic pickups, as well as the GraphTech Acousti-Phonic system/preamp with piezo pickups. Does anyone have any help on how these would be wired? I know the magnetic pickups need to go through the Acousti-Phonic system to work, but I’m not sure where/how the Bartolini preamp comes into play. Any help is appreciated!