Looking for possible issues for this. Noticed from a band recording last night that the tone of my A string gets significantly thinner when playing around the 9 to 12th frets. What are some potential issues (and solutions) that I could do for this? I was playing a Fender American Deluxe Jazz in active mode through a Ampeg SVT3-Pro and 4x10 cab. Could it simply be an EQ problem (had a drop in EQ around 300Hz to counter-act potential mud in the room) or something far more sinister?