Curious on A/B box noises

[hose]

Curious to throw this out there: I recently built this A/B box: http://www.fulltone.com/PDfFiles/AB_switcher.pdf
I am using it basically to have one side go to a tuner and the other to the rig.

Here is the question: When it is switched to the side going to the tuner you can hear some noises (low level "popping" type sounds) through the speaker. These sounds correspond to the tuner coming on and going off as you tune each string. Curious why this is the case. Thought it would be totally silent when the A/B box was switched to just the tuner side.

I may mention too that the one side of the A/B box is just going to the tuner, nothing else (ie: out of the A/B box right to the tuner> nothing then plugged into the output of the tuner. So just the input is plugged in> which is coming from the A/B box out).  Thought: Would plugging in a Dummy plug (grounded 1/4") into the output stop this?

Thanks so much. I do very much appreciate your time.

Best regards-

[jkokura]

I doubt the dummy plug would help. I can't answer your other questions with any surety. Sorry,

jacob