It's hard to explain what is happening.  Today I playing on my line 6 150 watt spider IV amp and using the FBV Board... I was actually showing someone the features of the amplifier and the board, and when I stepped on the pedal to activate the Wah effect on the FBV board it started wailing through the amp with this screeching high pitch feedback like signal.  This freaked me out so I shut everything down, disconnected the board from the amp and reconnected it, turned it back on.  Then when I turned the wah pedal on it came through with this really crazy soudning buzzing noise, the buzz would fluctuate with the wah pedal, but the guitar signal stayed constant.  I plugged the same FBV board into my 40 watt Valve 112 bogner and the wah pedal worked fine.  So I plugged back into the 150 Watt Spider IV and it continues to make this crazy freaking noise when I try to use the Wah pedal.  Has this been an issue for anyone else, and is there any way it can be remedied?  Thanks...