Glenn Frey Guitar A electric guitar pickup is essentially much like a powerful mike coil. For many years, active microphones have been sent with the style coil attached with the primary of the microphone's transformer, and not called to ground (‘floating'). The microphone's event is typically linked to the wire shield, which is linked to the microphone amplifier's soil (see Rane's site for more discussion).
By and large, active microphones are extremely calm units consequently of the mix of transformer isolation and balanced, floating transmission lines for the duration of, along with protected, humbucking coils.
Therefore why not instruments? Guitars are notoriously affected by noise. Humbucking pickups are just an incomplete (though important!) solution. The obvious alternative would be to float the guitar pickup to a balanced output, being a microphone. A similar idea was printed this 2001 patent software like this Glenn Frey Guitar?