vibes :)

Well, what is the style called then?

I mean something like here at 1:07 https://youtu.be/GLm5Bfnzfh8

If the measurements found online are of any substance, just applying EQ to the 7506 should already do a lot.

In that case, try something like this and try what I described above.

Is this Spotify eq you mention exclusive to the app or is it using some system-wide built-in graphic eq?

In either instance, the easiest and most reliable way I'd say is to find some pink-noise on Spotify (if the eq is exclusive to the app and not something applied to every app capable of audio playback) and adjust the EQ so that it sounds as even as you can make it with what you have.

If there are treble spikes or too much bass, etc you will be able to hear it on pink noise and if pink noise sounds balanced so will music.

Really nice explanation even if I can't quite visualize it or understand it perfectly.

So I don't understand the whole phase thing but the part about phase cancelation and consequent dips made me go "aha, I see" because I have AKG K371 and HD560S that both have notches where they get really quiet but also one side gets louder (K371 much worse though) and I can't fix it with EQ.

Both tonality and Soundstage mostly have to do with frequency response relative to your ear-anatomy.

Frequency response = volume of each frequency on the spectrum, when measured, forming a curve that indicates a certain sound profile.

Tonality = overall balance.

Timbre = how smooth and consistent the tonality is because if it deviates a lot, if there are significant peaks or dips in several places it will mess with everything, though my experience is that it's a bit different on headphones as opposed to in-ears.

Sound stage = really just a blanket term for treble extension and good tonal balance. In other words, right amount of lows, mids and highs.

Fun to play around with once you get familiar with EQ.