I bought a custom shop Gibson J45 as my posh acoustic and it was fitted with a K & K pick-up.
I use the guitar mainly for recording, and had been blending the pickup sound with a condenser at the neck join area . . For my ears the sound was pretty stunning,.
I toyed with doing an unplugged portion at my gigs, and decided that I?d try the pre-amp to get a little bit better control without having to knob twiddle at the desk. . .
The pre-amp makes a HUGE difference, the sound is very rich and big through a pa , and also great in recording, I now frequently don?t bother with a room mic for an acoustic rhythm part.
It is also very simple , which live I think is important in a live situation.
I don?t have any other pre-amps to compare it with , so depending on your experience my thoughts can be taken with a pinch of salt.
I also use it as a DI box for bass guitar , and again it gives a depth and clarity for recording that seems to blend perfectly.
I take a while to select products based on internet research more than trialling gear but it would seem obvious to me to pick this pre-amp if you have the pick-up ?