Hello. I have an Acoustic B200 combo amp. I don't really understand the purpose of the notch knob. The manual says: Active -10 dB notch at frequencies from 50Hz to 1kHz – approximately 250Hz with the frequency knob at 12 o’clock. Why would I want to notch a frequency when there are 6 EQ knobs there? There is no knob position that turns off the notch? Has anyone opened the amp and disabled the notch knob? How easy is it to do? I think it is a great combo. Sounds nice and is plenty loud. The notch knob is the only thing I don't like about it. Thanks!