Audiophile Tool Bingo

Yes, your ears are the best "gadgets" extant, and are only supplemented by all the gizmos and do-dads. Use of tape measures and lasers help to narrow down things  in order to lay down some kind of baseline.

Measurements and microphones can "hear" things  you can't and still won't be able to after using them simply because we're all deficient (or overly sensitive) in some aspects of the frequency range, so good luck with that. 

In the end, it will always be your ears that decide.

All the best,
Nonoise

Eric I would add:

Mini Screwdriver

Hex wrenches

DeOxit

And from your list I have:

Voltmeter

Measuring tape

Laser Measuring tape

Analog level

Making my score 7.

Good lights;

good magnification;

@whart   Just what do you magnify??

For starters, Erik, useful in phono cartridge set up. I use different magnifiers for different purposes. I wear one of those illuminated eyeglass magnifiers to brush cartridge while playing, but that isn't exactly set up. Anything small I need to see, good light and magnification helps.