Hi all, I have a custom-built active bass with 2 pickups (Bartolini Music Man and a piezo) and volume, blend, treble, and bass knobs. When I turn the bass knob anywhere near maximum, I get pretty severe distortion on the low strings. I have a fresh battery in there, I'm running the bass direct in to my audio interface with plenty of headroom. So it seems like the internal preamp must be clipping. My dad built the bass almost 20 years ago and doesn't remember the electronics used (the preamp is unlabeled). He was a classical guitar maker at the time, and this was his first time making an electric instrument. I don't remember if the distortion has always been there. I see from this thread that cheaper preamps have low headroom. Is this a matter of upgrading the preamp? Any recommendations or specs to look for if so? Worst case I can just keep the bass knob turned down, but I do like how it sounds cranked when it's not clipping. Thanks!