This article is a report about several interesting aspects of the project. The capacitance of a guitar cord can attenuate the high frequencies and lower the tuning of the resonant peak of the pickup. The input impedance of a guitar amp, mixer or effects boxes can attenuate or distort parts of the guitar signal. And because the guitar signal is not very robust, external noise sources and grounding can become serious problems. The guitar's volume control further increases the output impedance, multiplying the problems.
Piezoelectric pickups suffer similiar problems, though the exact mechanisms are different.
A preamp can address these problems by acting as a buffer, providing the guitar pickup with an optimal high impedance load and driving the cable, effects boxes, and amplifier with a robust signal. It preamps anything it touches. You get most of the advantages of having a preamp installed in your electric guitars, basses, or piezo-equipped acoustic instruments without having to carve up the your favorite instrument. Additionally, it's easy to carry extra Preamp Cables as backups in case of failures. Maybe exotic pickup mixing or specialized EQs or boosts.