I have a Hartke LH500 if that helps. simple controls...volume, bass, mids, treble.
I had the bass plugged in ODB-3 which was plugged into a tuner which is plugged into the amp.
I even used a different amp head with the bass going directly into the amp, no pedals or anything connected and it was still doin it.
Black'n'Maple Club #493, Squier CV Club #153