L.R. Baggs Control-X Mixer/Preamp

First off...this preamp and its controls are superb! I love them and they are easy for the end user to navigate in a stage setting. However...there is some great difficulty in wiring it into a guitar as it was designed to be compatible with a Stratocaster. If your guitar has 2 Pickups, 2 Volumes and a 3-way Toggle Switch, you will need to get creative to get it to work with your control configuration.
I've attached a photo of a wiring method that worked for me on a guitar with.... 2 Pickups 2 Volume (Independently wired & with Push/Pull Pots) 2 Tone 1- 3 Way Toggle.
The Jack that is supplied with the CTRL-X was not compatible with my guitar, so I opted for a Fishman "Switchjack" in its place. It has Tip/Ring/Switch/Sleeve capability. You will see that my summed Orange wires from the CTRL-X are not finished in the drawing. If you can, send them to a separate Volume Pot or a Master Volume for Piezo only volume control. Or, send them to the Tip/Output and the CTRL-X's Blend Pot will act as your Volume control for the Piezo. Either way will work and it depends on the rest of your controls and how you lay them out. I hope this helps in your decision to use the CTRL-X, especially if you have a TOM bridge. It's a really slick and professional set up for adding piezo to your electric guitar.

I bought this kit to give a preamp to my fishman undersaddle piezo guitar.

The main reason to get it is
1) you have one output and want to use it in stereo. If you don't care, still great way to do it 2) you have a piezo bridge, be it fishman or baggs 3) you want your magnetic pickups to stay untouched by onboard eletronics
Pros 1)beautiful amplified acoustic tones 2)separate on board volume
3)on board phase switch keeps conventional magnetic pups untouched by preamp system. Can be used when you only have one output jack (as opposed to a double one in some guitars)
4)comes with everything you need, including a stereo jack.

Cons
You have to drill to make a hole. It can be scary but everything went great on my guitar.

This is a preamp/mixer board with gain adjust that will work with any piezo signals summed together (all signals joined and all grounds joined). I will say there are no helpful wiring diagrams out there unless you're installing it on a Strat. I installed it on an Epiphone Les Paul and scratched my head several times coming up with a good wiring plan I thought was well worth the effort!

Be warned, if you're installing on any solid body there will more than likely be a need for some wood working to get the pot to reach past the top's face. The push button was also in need of modifying so it would reach. Again, I thought it complimented the T-Bridge wonderfully!