As advised, there are many and various ways to adjust the sound made by a guitar.
I interviewed Scott Gorham from Thin Lizzy a couple of years ago, and at the after-gig party, Scott introduced me to the guy who looks after his amps, and confirmed that the work he does on Scott's amps is totally secret, so no point asking him about it!
I did an interview with ben Thatcher, the drummer from Royal Blood, and walking around the stage during soundcheck, I had a good long look at the amps and pedals set-up for Mike Kerr. Mike famously refuses to discuss his set-up with the tech. magazines, and I knew that Bass Guitar - for whom I also write - would love a quick shot of his pedal boards and amps, but that's not ethical so I didn't do it.
Tempting though!!!!