@iampoor
I presume the bias you're talking about is marked VB, being fed to IC1A's inverting input via R7 & R19?
If so, remove that VB/R7 combo, instead attaching the non inverting inputs of IC1A & IC1B to your virtual ground. The inverting configurations here mean that IC1A will drive current through R18 to bring it to 4.5V to match the + input, and IC1B will do the same via R24, pot U$5, and R26.
As the active portion here is decoupled from the rest of the circuit by C8 and C14, it will "float" on the virtual ground, ensuring correct opamp behaviour.
For good performance, google virtual ground circuits, and take the advice you can find - you probably don't need a buffer if your divider resistance isn't too high, since you're only feeding the high input impedance on the two + inputs, but a capacitor over the bottom leg would likely be a good idea.