So I play an esp passive fretless into a zoom b3 and a hartke combo. Not traditional I know, but hey it works for me. I recently bought an art tube mp. I stuck a Mullard Russian tube in it and plugged in my bass. All I can say is wow. They market these for vocals and acoustic guitars. It rounds out and fillls in the low end without losing clarity, and makes my whole rig sound like an old tube fliptop or something. It's awesome...and inexpensive...
