I can't say enough good things about the Knockout. It gives everything a boost. The clean sounds out of it are superb and when used with an overdrive, it sounds fantastic. The two filters let you set your low and high end just as you like it and the dry knob lets you tweak the sound. There's so many sound variations you can get out of the thing and still keep the character of your guitar. I wouldn't have considered it before the guy in the shop hooked me up (he was cool - he kept hooking me up to things saying "you've got to try this"). Once I heard it, I couldn't leave without it.
