Most vintage guitars suffer from steadily deteriorating magnets in their pickups, since permanent magnets aren't really forever. The Super Hard-On's input impedance is so high (>5 Meg) that it refuses any current flow from your pickup... maintaining the most magnetic field around each string, so you can hear exactly what your pickup sounded like the day it came off the winder. The ouput level can exceed 8 volts peak, and when it finally distorts, the wave is shaped like triode overload, not fuzz. ALL OF THEM HAVE LEDs NOW!