Volume Level "Front Input" vs. "Alternative Input"

  • During our performance last weekend I had to change from my guitar-wireless (Alternativ Input) to a guitar cable (Front Input), due to failing batteries.
    After then the guitar-level in my monitor increased dramatically. (Btw: Normally the level of my wireless-receiver is the same as if I play via cable).
    The manual just says that there should be only a slight difference in sensitivity.