I sent it back to Dunlop and they said the could not duplicate the issue, but say they replaced the board anyways. I use it 2nd in line after a wah, but have tried it before as well (straight in after the guitar, not in the effects loop, but it still does it in the loop). It does the crackle whether on or off, no matter which guitar or amp I use.

Music - Dunlop - Manufacturing Dunlop JD4s Rotovibe (with )