In the four forums I regularly make a nuisance of myself in there is a steady stream of questions/problems of a "technical" nature. Favourites are speaker impedances and the related safety or otherwise of their connection to amplifiers. Hum loop troubles and leads and connections, DI boxes (I am forever sorting confusion re 10:1 boxes and things like the Art!). The bottom line is that unless you are very well heeled or have a friend who is an electronics whizz (but otherwise stupid) you will not get very far past "plug and play" and most forms of experimentaion will be forever denied you.
I am constantly advising guitarists especially to buy a 10quid DMM. How do they test pedal batteries FCS! Now I find my favourite magazine is plotting against me!
And Sir! I bet have read more SoS than you have and lack of decent support paperwork is hardly EVER commented upon.
The sensitivity question: I was intersted in a small, new AI that could be used out of the house with a laptop. I have a suitable one in the Fast track pro but its mic amps are woefully short on gain. I therefore asked the AI makers for a "proper" specification (they have to have one at some point to make the damn things!) Much emailing later I was no nearer but having come to the conclusion that all that needs to be done is give an input voltage needed at max gain to give XdBFS, ...wrapped