Graph Tech Ghost Piezos - Passive Volume Kit
 

http://graphtech.com/product-10-2/

This looks like an interesting alternative to using a preamp with the ghost piezos. Has anyone tried this passive kit?

That'll work if you're routing the piezo output to it's own jack - if you want to mix the piezos with magnetic pickups to a single output jack you'll need a preamp built specifically to do that.

Agreed. This would be for a piezo-only bass.