So I recently bought a Boss TU3 for my bassist. (I'm wiring up his pedalboard for him.) I decided to put the TU3 first in line, then comp, then Sansamp. When everything was plugged in, the TU3 powered up, but couldn't "sense" the notes out of his bass. (Spector, EMG jazz bass pickups, active). His bass, plugged directly into the amplifier, works and sounds fine. I tried the tuner with my guitars, and my passive Jazz bass, and it works fine. Has anyone ever had issues with an active signal into a tuner being too hot? Or is it because it's a low impedance signal?