Awesome game and great visuals.
Half of the time I didn't know what I was doing, even after reading the manual. I guess that in a sense the manual adds to the feeling of uncertainty rather than explaining clearly the mechanics, which is another thing that I liked. I think you can actually turn this into a great tool if you add the option for custom songs.
The only thing that I consider a problem is that it wasn't clear what parts each channel affected. Maybe the oscilloscope could be split into channels after the effects. Also I took a while to understand that the effects on the left needed to be toggled on.