JazzTom said: yeah but , technically, a booster pedal can be connected to a jazzmaster pickup?(is what it seems)
and what is the vibrato channel function?
Why not? You can wire a pickup straight to a jack plug and plug it into the pedal. All it technically is is a very basic microphone, so by boosting the gain of a pickup outside of a guitar next to the amp would create some crazy feedback noise, which is not unreasonable seeing as it's Sonic Youth we're talking about.
As for the vibrato channel- it's a channel that has vibrato on it, presumably, the clue's pretty much in the name.