Let's see, too bright. Solutions:
flats instead of rounds
use 250kohm pots instead of 500kohm (passive bass)
increase tone capacitor to .047, .068 or .1
pickups with alnico II magnets instead of alnico V, VIII, or ceramic
turn down the tone (passive) or treble (active) on the bass
trim (one of my cabs has a switch, the other has a rheostat on the tweeter) or cut the tweeter in the cab
turn down the treble on the amp (remember, most bass amps have "flat" as the 12:00 position, not full clockwise like a conventional instrument tone control)
pick/pluck more towards the neck
use the neck pickup instead of the bridge pickup
humbucker instead of single coil
fingerstyle with the side of the finger, as does a double bass player, instead of the tip of the finger
block of foam under the strings at the bridge saddles
bleed capacitor to ground, say, something from .001 to .01
One, some, or all of these will darken a bass. I recently purchased an Ibanez SRA305 with the EMG-HZ pickups. Great pickups. The neck was a little too bright. I bridged the neck volume control with a 1 megohm resistor to bring the effective value down to 330kohm, effectively simultaneously increasing the load to ground and decreasing the resonant peak of the pickup. That was all I needed after the new strings settled in.