Equalisation pour casque- Equalisation for headphones

Not sure how much programming you are will to try but here's a nice site with quite a lot of data, including equalization data for both your headphones.  The curves they give target the Harman curve but they can probably be adapted either by hand or using "some" programming to create your own curve to target the HD 540 rather than a Harman curve.

The site also has quite a bit of information about equalization apps and tools for different OSes (including phones/tablets).

Here's the site : AutoEq on GitHub

And links directly to the two head phones that interest you :

HD 540

HD 599

Hope that helps a bit.

I am under the impression that neither of these work quite the way you want (as a simple fixed or parametric band equalizer).

The "Equalizer" button on the main UI opens a dialog and if you hover over the "?" symbol you will see that it explains that the equalizer is not a traditional one, but affects the instrument model directly and adds compensation as well to keep loudness the same.

The "Equ3" panel in "Effects" is described in the manual as : "The EQ3 effect is a simple 3-band parametric equaliser. Dragging control points on the interface will change the cutoff-frequency and the gain of each band. Pressing the ’shift’ key while dragging will change the Q factor of each band."

So Equ3 is probably close to what you want, but I think not quite what you want as a 3-band parametric seems too limited for your needs.  You can combine multiple Equ3 effects but this seems quite complex to get to do what you want.  You might be able to smooth out the offending HD 599 "bass bump" using it.

This might be worth exploring more on this site and perhaps on the Equalizer APO site to see if a solution to the latency issue can be found.  Maybe you could explain the system setup you use (CPU, what sound API you use and if you use a sound card like a Focusrite or similar) and perhaps people can offer some suggestions.

Any external equalizer will add latency, nothing to do about it, but you're talking about 2 instances of EQ3, there are 3 AFAIK ? And from what you described, you only need one, don't you ?
Edit: some sound cards are equipped with DSP's, which allows latency-free EQ, what are you using ?

Tout égaliseur externe ajoutera de la latence, rien à faire, mais vous parlez de 2 instances d'EQ3, il y en a 3 sauf erreur ? Et d'après ce que vous avez décrit, vous n'en avez besoin que d'une seule, non ?
Edit: certaines cartes-son sont équipées de DSP's, ce qui permet des EQ sans latence, en utilisez-vous une, si oui, laquelle ?

Du haut de gamme ! Mais dans ce cas, je ne vois comme solution qu'une interface USB avec DSP comme La Tascam 208i ou la Motu Ultralite-MK5. Avec plein d'entrées et de sorties qui ne vous serviront à rien, malheureusement...

Top of the line! But in this case, I can only think of a USB interface with DSP like the Tascam 208i or the Motu Ultralite-MK5. With a lot of inputs and outputs that won't be of any help, unfortunately...