I agree that bass and treble sliders would be good.

However, in the meantime, while you wait, I suggest trying to use the Loudness slider in place of bass and see how you do with that. It ends up acting pretty much like a bass control, only better because it's dynamic as you bring the volume up and down.

As far as treble is concerned, I don't ever have a need to adjust those frequencies on the fly, I only ever adjust low frequencies as conditions change.