Q: “I’ve heard that Grace can modify a 101 to a high-gain version. Does the impedance change once they’ve made the modification?”
A: Grace offers a High-Gain version of the 101 preamp which shifts the gain range from (+10-+60) dB to (+20-+70) dB. Typical users of the High-Gain version of the 101 are ribbon mic owners who need a bit more gain for recording at a distance, finger-picked guitar recording, etc (often times, vocals, amps and cabinets will not need the boost in gain). This modification does not affect the input impedance of the preamp, which remains 1.6k ohms. The changes are made to the amplifier gain staging, which result in an uncompromised noise and distortion performance.