I've tried them using Egnater Tweaker 15 on two guitars: a Harley Benton SG clone and an Epiphone Les Paul. While it improved the sound of SG tremendously, I still wasn't happy with the guitar sound in general. Though they did magic to the Epi - it's one of my favorite guitars with a chime and a very dynamic sound. I dialed many tones with it: from classics like Mark Knopfler (not exact, but good enough), David Gilmour, Brian May, and Santana to the stoner rock/metal (Kyuss-like) and co. Not too great for the tight high gain, though (or it's just that I didn't manage to get there).