Simble Predriver is not just a preamp, it is a preamp/booster/compressor/upper harmonic enhancer.
This musical tonal combination is totally adjustable with your picking attack and guitar volume pot.
The amount of boost depends on the input signal level and HOT/COOL switch position. Maximum is about +10dB on lower level notes and average is about +6dB.
Simble Predriver’s special circuitry uses low noise transistor with high input impedance (over 2 Mohm) so you can boost even piezo pickups without tone loss.
The output impedance is 50 Kohm so it works even in front of fuzz pedals.
The power consumption is very small, if you remove the input jack when not playing you can use the pedal with a 9V battery for few years!
Very good condition.