Just wondering if pedals that can run off a 9V battery absolutely have to have a battery in them in order to be powered by an external power source. Is it possible to run them without a battery at all? I have been doing both with certain pedals, but i'm wondering what the effect is on the pedal when you run it with/without the battery in it. I had a Keeley Comp one time that quit working completely, but when I replaced the battery it came back to life. Could it have been possible to run it with no battery install at all? Thanks!