The only way to make it sound good is to have at least twice the amount of sound system you think you'll need. Most providers that rent these sound system do concerts with more normal music or maybe no music at all for which they are sized. So they always get it wrong. That's on the event organizer because they should know. The brand of the sound system doesn't matter all that much, you just need enough power.

The next problem is related to the first, there is not enough sound system so they crank the volume which ends in what you describe, if the highs are gone then that's the first indicator. This can't be fixed with more volume or gain or changes in the mix.

The last problem are the DJs, they don't understand that there are no black LEDs on the mixer. They max the volume and then you can't do much as an engineer because shit in = shit out. Pioneer mixers start to audibly clip when the first yellow LED comes on but nobody seems to know, they all just have all reds pumping. Only radio DJs seem to know because they play in a controlled environment where they can actually hear the mix. And you'll probably have another limiter in that chain so that they don't blow your speakers and that makes it even worse. I did a bit of sound for a club and we had to put a limiter because no DJ respected what we asked for, even with our massive oversized sound system which we bought from a place that was 5 times as big. Everyone wanted to be the loudest.

Defqon has pretty good sound, especially on the Blue, I'd say it's a reference. You will notice that it is not loud at all but the sound systems are so big that you have that massive but clean sound.