OK, I've found two different Preamps that pretty much fit exactly what I want in a preamp. One is an Agulair OBP-3, 5 knobs (Volume, Blend, Highs, Mids, Lows) and one switch (switich frequencies between 250 and 800Hz). The other is a Bartolini with the same settings. What do you guys think would sound best with Jazz style Pups? Also the bass I'm looking at to put it in is chambered with an Ash body, if that would affect it all.