Most people know that the audible spectrum runs from 16–20 Hz up to 20,000 Hz (20 kHz). Some people have a wider range; for some, part of the spectrum is felt rather than heard.
The most common equalization mistake is chasing the widest possible frequency range. It is fortunate that there are hardware limits - otherwise we would be seeing ranges from minus to plus infinity. For a maximalist, even infinity is probably not enough.
Even the most premium and powerful systems should be limited at the bottom to around 30–40 Hz. Those frequencies are the most energy-intensive, and they can produce unpleasant, nausea-inducing sensations - especially in long sessions and especially for older audience members.
In smaller rooms - where bass behaves differently - you can safely cut at 50–60 Hz. You can always shift the high-pass filter down a little if the low end feels thin.
As for the upper range - the so-called brilliance frequencies - this was a genuine revelation for me: in 90% of cases they add tension without carrying any useful information. Above 16 kHz in a live context you can cut without a second thought. I usually place my cut at 11 kHz, and the mix only benefits. Modern records are often equalized with a roll-off above 8 kHz - which feels too aggressive to me personally, though I will admit the vocal and instrument clarity in those mixes is excellent.
The takeaway: from the entire audible spectrum, we only need about half of it. The system stops straining, and those constraints actually improve clarity. Minimalism applies far better to sound than maximalism does. We sometimes overestimate ourselves, assuming that our subjective perception is exactly what thousands of listeners want to hear. More often than not, that is not the case. There are many factors to account for - including the age of your audience.
What do you think - is there something in this?