I built this little device because when I purchased my Mojo Fly from my local music store, they never gave me this "special stereo cord" mentioned in the owners manual. After thinking about it a little bit, I decided that I would rather have a box that split the stereo signal into two seperate signals. I also like this idea because it means that I don't have to have a special stereo to mono cord which can break & be difficult to replace and it allows me to use whatever cords I want to connect to the amplifiers.
Building it is very simple. For my prototype, I used a plastic RadioShack project enclosure which measures 3"x2"x1.5" (Part #270-283). To wire it, I simply used a stereo input jack and connected
each stereo signal to a seperate mono jack, one for the magnetic pickups and one for the piezo
pickups. The grounds are all connected together, but the two signal grounds can be seperated by using a ground lift switch. I haven't tested this with all my amps, so I am not sure if this is bulletproof or not, but in theory it should prevent hum from ground loops caused by two different
amplifiers sharing the same ground. Cost to build the splitter box is about $10 or so.