home-made piezo pick up to a fishman powerchip?

I have a J-bass I wanted to put piezo pu's to mix with the magnetic pu's and I have a home-made piezo pick-up morely like an under-saddle type you might find in acoustic guitars, now can I use the fishman powerchip (preamp) so i could mix my magnetic pick-up with single output? That would give me a separate volume to the piezo pu.

I'm planning to put the piezo pu under the saddle bridge then to fishman powerchip while the sum out of magnetic pu's will meet in the end of the jack like the powerchip installation said. http://www.fishman.com/uploads/products/documents/179.pdf would that work?

Do the fishman powerchip works only with fishman piezo pu's or it can be used to other piezo pu's? thanks already for the answers I really appreciate help on this