For the uninitiated wondering about some of the EQ statements in this thread…
For IEMs, look at EQ as a complete last resort. IEMs are designed to sound the way they sound. If you wish you had a little more bass/mids/treble, think about doing some research into an IEM that will suit your preferences that sounds the way you want it to without any EQ help.
Generally headphones can benefit from some EQ because they usually are harder to tune for because they usually only have one driver. Again, the same rules apply, apply as little EQ as possible targeting a known FR target curve or your own personal preference curve making the least amount of boosts or cuts possible. Cutting is usually always preferred over increasing EQ gain.
EQ should be used to correct issues with the transducers FR. NOT TURN IT’S FREQUENCY RESPONSE INTO SOMETHING COMPLETY DIFFERENT!
There are certain instances where the transducers technical capabilities are so strong that you can apply EQ to modify it FR without harming the integrity of the source too much. Example the Tin P1 for instance. This is what we usually refer to as an IEM that takes to EQ well. Many do not.
General EQ tip is to use as little as possible. Ideally none.
If you are using EQ just because you enjoy playing with PEQ sliders because they are fun to play with, you’re probably not an audiophile.
Do not form IEM/headphone impressions/assumptions with EQ applied. You can not give accurate impressions to others of an IEMs capabilities when you are hearing something obviously different than everyone else, especially if you’re using EQ on an IEM that takes poorly to EQ and wondering why it does not sound detailed. It’s because you’ve compromised that aspect of the transducer with EQ.
I’ve been doing EQ work in mixing and mastering of audio for over 20 years. It’s an artform that I will admit I have still not mastered.