Some Ibanez Artcore instruments were built with low impedance pickups. I am not sure of the impedance, but I think it was in the neighborhood of 1.5 k Ohm, compared to the more common 10 to 15 k Ohm impedance of many pickups. If a pickup in the 1.5 k Ohm range has a tone control made up of a 500 k Ohm pot, and a 0.05 uF capacitor is installed in your bass, you could replace the volume and tone pots with 50 k Ohm audio taper pots, and the capacitor with something in the neighborhood of 0.22 to improve the effect that the tone control has on the output.
Check the DC resistance of the pickup, and the pot and cap labeled values as the first step.
As an alternative, you could replace the pickup with something better than the stock pickup.
Edit: kbd responded as I was typing.
Edit, again: I have an Artcore guitar, not bass, and I think these are really nice instruments. I put flat wound strings on mine, and it is one of my favorite guitars. Aside from the tone control issue, how do you like the bass?
Third edit: My post is based on a single pickup configuration. Before taking my advice, look at the way your two pickup bass is wired. Does Ibanez provide a schematic for your bass?
