Bear in mind that a lot of modern softsynths don't roll off like old hardware did like M1s, D50s, DX7s etc in the 90s which often rolled off around 11khz or so (mainly due to the sample quality at that time and other factors). Many will push frequencies way higher than that, especially if they have some noise mixed in some of their sound oscillators. When you're boosting your master you're gonna also boost that top end from the plugins.

You may find that rolling off some of the synth layers at 11k+ a little and leaving just the hihats and other similar real top end layers also helps with the harshness of your final master.

 

bx digital v3,
soundtoys sie-eq
acustica audio almost all

 

GEM Dopamine

 

Rather than using EQ, try multi-band compression and/or saturation.

 

There are a lot of tricks and many eq's,
You have to try them to find out good one with your taste

 

I didn't see anyone mention Acustica Audio Azure. It's sampled from a hardware signal chain where the main mastering EQ is a Knif Soma.

 

any EQ with oversampling option will work just fine, alternatively crank up the sampling rate in your DAW settings
this will showcase you why thats important: https://admiralbumblebee.com/assets/InfiniStrip/InfiniCramp.mp4

also get an EQ with baxandell curves, i think fabfilter and even waves Renaissance EQ has them
there are also good alternatives like maag EQs air band, pultec style EQs, maybe clariphonic

 

Btw; all synths of the 80s, two with some PCM sample elements.

 

Well corrected - the scary part is I remember them being pretty new!