The present invention relates generally to guitars, guitar pickups, and guitar equipment.  More particularly, this invention pertains to digital guitars, multi-signal guitar pickups, and digital guitar interface devices. 
Guitars are well known in the art and include a wide variety of different types and designs.  For example, the prior art includes various types of acoustic and electric guitars.  These guitars are typically adapted to receive analog audio signals, such as analog microphone signals, and to output analog audio signals, such as analog string signals (analog audio signals generated by guitar pickups when guitar strings are strummed) and analog headphone signals. 
The prior art includes monophonic guitars, i.e., guitars that output a single string signal when one or more of the guitar strings mounted on the guitar are strummed.  The prior art also includes guitars that output a single string signal for each string mounted on a guitar.  The latter type of guitar is generally referred to as a polyphonic guitar. 
All of these guitars have a common disadvantage—they all receive and output analog audio signals.  Analog audio signals are susceptible to various kinds of electrical and environmental noise that can degrade the quality of the analog audio signal.  This is particularly true in environments where the analog audio signals are transmitted through cables exposed to electrical power cables or other cables that are also carrying analog audio signals.  Regardless of the cause, degraded analog audio signals are undesirable because they are unpleasant to listen to and do not accurately reflect the audio output of the guitar. 
Although conventional guitars, and the associated noise problems discussed above, have been around for years, no one appears to have addressed this problem in the prior art.  Thus, there is a need for a guitar that can receive and output audio signals that are less susceptible to electrical and environmental noise.