Dumb question pertaining to Treble Booster output.

[Burstbucker]

Please pardon my ignorance but how much is the voltage increased when going through a Treble Booster?

I measured 7.1VDC between ground and the hot lug of my Treble Booster's "Boost" pot.  I know that the voltage output from a standard guitar pickup only puts out millivolts but  I was wondering how much hotter is the signal when being boosted by the Treble Booster?  What's the voltage being sent to the amp's input jack?