I was playing my American Standard with BassMax and Fishman Pro-EQ into WM-12 yesterday and got an unusual kind of feedback. Usually, if there's feedback, it's a low frequency where the top starts resonating. This time, my G string would have a high frequency ring whenever I hit G on the D string...couldn't figure out how to chase that one away...certainly not the phasing switch. We weren't playing all that loud...small amps for guitar and harp, no drums. Suggestions? I've usually used an Underwood but wanted to give the BassMax a try...quite a different sound between the two designs.