For starters, ever heard of negative feedback and how to use it to control gain ... but then, you already knew that, didn't you?
Ever heard of "programmable gain amps." Etc., etc. ...
The problems in design/construction can be as simple/difficult as you choose to make 'em. Nothing along these simple design specs you list comes even close to impossible, nor even of great difficulty ...
No wonder "they" have gone offshore, seems a chit-load here has become dumb-struck!
Regards, JS