Hello, I have EMG pj pups with BTC preamp in one of my basses. If I do not have the volume wide open, I get "distortion" (not a ton, but enough to drive me insane and not want to play the bass). With the volume wide open, it sounds great. Dialed back 25, 50, 75%, I get the distortion. Didn't start happening until recently. Checked battery. Checked cables. All other basses working properly through same set up. Thoughts? Thanks.