I've wanted a booster of some description for my guitar for some time, and finally found this on eBay. For £13 +£5.50 shipping I thought I couldn't go wrong! I had actually bought parts to build a preamp that cost about a tenner, but this was going to save me a lot of headaches.
Currently on sale here: https://www.ebay.co.uk/itm/Active-Onboard-Guitar-Preamp-G-501/272909922087
Sold by Gandalf Electronics
Made by AnalogWorkshop.freecluster.eu
It really was that simple to install. Follow the instructions, which amount to where to solder the wires (ie there are no modifications as such) and you're away.
Of course, I wanted something a little different, so I wired in a push-push pot to turn it on and off and a stereo jack to turn off the battery when unplugged.
On offer is up to 21db of gain which you can set with a PCB-mounted pot.
And it sounds GREAT!
21db is a LOT of gain, so I dialled it down to about 12-15db, which is about right to "push you over the cliff". It goes WAY past 11, but then you could turn it down further to act like a small nudge of gain.
Overall, I'm super impressed. The customer service was fantastic as I got several emails offering help with installation, which I did take them up on. They were very helpful and friendly.
There are two other models for sale : 6db and 28db, just in case you need just a nudge, or you want to "blow the bl**dy doors off."