WEBENCH® Tools/TAS5768M: bass treble setting method

Tool/software: WEBENCH® Design Tools

Hi,

I want to set bass and treble on TAS5768M by using PPC3,

what is the right method to do that?

for now I am using this method:

for bass setting I use low pas filter, if I want to increase bass I am shifting the cut off frequency

set

bass level1 :low pass at 1800Hz cut off

bass level2 :low pass at 1600Hz cut off

bass leve3 :low pass at 1400Hz cut off

bass level4 :low pass at 1200Hz cut off

.... and so on

set

treble level1 :high pass at 300Hz cut off

treble level2 :high pass at 500Hz cut off

treble level3 :high pass at 700Hz cut off

treble level4 :high pass at 900Hz cut off

... and so on

individually.

is this the right method for setting bass and treble?   If yes how will I set minus bass and minus treble?

OR is there another method for setting bass and treble like that:

define a frequency for bass, for ex: 500 Hz

and adjust the gain level above 500Hz;

nominal gain 12dB,

set

bass level 1: 10 dB above 500Hz,

bass level 2: 8 dB above 500Hz,

bass level 3: 6 dB above 500Hz,

bass level 4: 4 dB above 500Hz,

.. and so on

define cut off frequency 700 Hz for treble 

set

treble level 1: 10 dB below 700Hz,

treble level 2: 8 dB below 700Hz,

treble level 3: 6 dB below 700Hz,

treble level 4: 4 dB below 700Hz,

... and so on

individually.

OR is the another method that I dont know?

I am confused to decide and use the best way for bass and treble setting

any help about this?