Fantastic Company
Fantastic Company - I can't recommend them highly enough.
They have a great range of innovative products. They are relatively expensive but very high quality and (most importantly) sound fantastic. I have three John East preamps installed and I have not had any issues in over 5 years.
They are improving all the time and moving forward: I first bought a J-Retro preamp about 5 years ago. It was fairly easy to install, but needed a small amount of soldering. I recently bought a Musicman replacement (MMSR 3 KNOB 3 BAND) and this was a completely soldering-free install (if you want to do it this way). I am not very skilled with electronics and certainly not with soldering, but I have had no problems with these installations.
Lastly, Jon has answered numerous, daft questions from over the years - he is very knowledgeable and really goes out of his way to make sure you are satisfied.