Reply to S4 on Pioneer Mixer: Mid/High Freq too loud

I've done 2 gigs so far, at the same place. Both times i had to put the channel (with the S4) EQ on the mixer down for the mid and high frequencies because they were way too loud.

For it all to sound right i set the EQ like so:
High -40%
Mid - 20%
Low - 0%

Any ideas on what is causing this oversteering sound in the higher frequencies?

Because there's no room for other gear i have to close the casing that is holding the CDJ's and mixer. Afterwards i place my laptop and controller on the closed case. So it's a real hassle tweaking the EQ after i've set up and started my set, as you can imagine

I have zero experience with these mixers. Is there some 'direct' or 'trough' switch that i can flip? Or is something else causing this?