I want to buy an amp where I can plug 2 basses in and control the volume and tone of each one. Mainly for teaching - so a student and I can both plug in. An amp with two inputs, but only one volume, doesn't work for me because one bass is always way louder than the other. Also, I'd like to use it for gigs where I double on upright and electric. So it would be nice if the amp sounds decent. I was thinking about one of the Polytones with multiple channels, such as the Sonic Bass II or Taurus. Any thoughts on this, or other suggestions? Thanks!