Its a Greer Light speed clone. When you step on the 2nd switch it activates a 800 hz boost. So it goes from non Tubescreamer to Tubescreamer kinda sorta. I like a cleanish boost but want the ability to go TS
An excerpt from "The Red Violin"
Not the scene I wanted, but Samuel L Jackson's character has this violin tested, and it resonates/sustains like crazy. The whole movie is great. It's on YouTube. Just fast forward to the testing scene, or watch the whole thing