Hm, I am affraid that simple approach with correction table works only if people use EQ in simple graphics mode (i.e. if they don't change default frequencies and Q factors for each band, only attenuation/boost).

Yeah, I've been turning my head inside out with this one all day. I think that you're probably right...the only way to do what Mark suggested would be to obtain all of the current eq settings, 'draw' the graph, add the adjustment and then factor the graph back into new eq settings that then get applied. I doubt that this is trivial to do, or desirable in k-space.

Assuming that everyone has default frequencies and Q factors in their eq settings would force users to make a choice of severely limiting their eqs or not being able to use this desired functionality.

IMO, the 'best' solution would be to overload bands 9 and 10 for bass and treble settings in 2x10 mode, or just band 5 for bass if the eq is being used in 4x5 mode.

Either have the user set up appropriate bass/treble frequencies and Q factors in these bands for all their eqs, or have config.ini/HiJack settable values that overload whatever the eq bands are set to.

Then make the dB adjustments easily accessible via the HiJack menu (lock all channels together!)

The only real issues are that you'd need to know whether the eq is in 4x5 or 2x10 mode, and to ensure that these new values stick if the user changes which of his 16 eq modes he is using. (Do you have visibility into this? Or is brute-forcing the bass/treble settings once per second an option?)

I've just played with some eq setting, and 200Hz,Q=0.15 and 8KHz,Q=0.15 seem to effect a reasonable bass and treble change.

As to clipping distortion caused by bass boost (definately an issue) I'd suggest reducing the volume as bass gets increased above 3dB boost. I don't know whether it'd be possible to change and limit the volume dynamically based upon what the current bass/treble settings are or not.