What decibel level do you listen at? What is ideal?

What would be ideal is if one were to listen at the same level that the engineer was listening at when he downmixed the track.  Then one would be subject to the same F-M curve and perceive the bass and treble in a similar context.

For some music, this can be quite loud.  Can your system recreate it?

The cut determines the decibel level.

When listening without any eq, the F-M curve is allowed to kick in and the volume control is used as a "focus knob", similar to a microscope or telescope, to determine the listening level.