i've never tried one, so take it for what it's worth, but i dont think a boost only preamp is very functional for upright. high pass filters are getting popular, and if nothing else, it's nice to have the ability to cut some low end with a normal bass knob if you need to. i like to have more control over the midrange on my upright too. that's the area that when boosted can help cut through the mix, or when cut, can tame certian feedback problems. for upright i like to have a 10meg ohm input too, although for the bass max you dont need that much, in the future you may decide to change your pickup. having said all that, the tech 21 (sans amp) Para Driver does all that for me, and works great with my electric too. (3 meg ohm input though). fishman pro platinum bass is my first choice for DB, but i've never tried it on my electric because the sans amp is so good.
