I have Etymotics too and used to listen with my Android phones. These days I just use TWS earbuds but the app/settings/etc. remain the same.

Ear tips and cables, resources for Etymotics: https://www.reddit.com/r/headphones/comments/10i5ha8/7_unused_at_a_local_amazon_warehouse_store/j5dpuij/

See here for more info about parametric EQ, squig.link comparison graphs, AutoEQ, ear tips, et cetera: https://www.reddit.com/r/HeadphoneAdvice/comments/10hhn0g/i_dont_notice_a_sound_difference_between_the/j58iozt/ and https://www.reddit.com/r/headphones/comments/109meb5/eq/j40cy1n/

Timmy from Gizaudio explaining squig.link and AutoEQ: https://www.youtube.com/watch?v=gpQalW_bjLQ

You can do (parametric) EQ with $8 Neutron Music Player or UAPP on Android. If on PC, the free (Peace) Equalizer APO. There are free apps on Android(/Apple) that can also do a good enough job, but most of them have those graphics sliders instead of parametric or just plug the numbers in EQ. EQ can also be used to help with channel or ear imbalances.

There's also the free Wavelet app that has the AutoEQ available now. And other free apps for more simple graphic sliders EQ, etc.

Don't forget oratory1990's preset EQ list, mainly for headphones but there's some IEMs there: https://www.reddit.com/r/oratory1990/wiki/index/list_of_presets

So I have my 16-bit and 24-bit FLACs with Neutron/etc. and then listen without EQ. Sometimes I'll apply EQ but I enjoy the stock sound of my Etymotics/TWS earbuds/etc. anyway (I spend a lot of time looking at graphs and reading the reviews so that I don't waste money/time) and so ya it's just there.

Parametric EQ is actually useful if you know your particular IEMs are not good with specific genres and like you have no other different sounding pair at the moment to switch for that desired genre. As with just a few numerical inputs or button presses, with parametric EQ the bass/treble/etc. can be altered accordingly.

Anyway TWS earbuds often have their own app and EQ system too. So things are changing for better (parametric) EQ everywhere.

It's expensive at $110-130 but the Qudelix 5K has a pretty nice user experience.

In theory any device you pair the Qudelix 5K with will have the parametric EQ still applied. There's also the various preset parametric EQs already available, just adjust according to your taste. Like you'll probably want to fine-tune a bit the AutoEQ values.

Qudelix is making a gaming/7.1/etc. device called Qudelix T71, so no successor to the Qudelix 5K for maybe 2023 or 2024: https://forum.qudelix.com/post/qudelixt71-12037543?pid=1334122761

The Qudelix 5K has no competition for value and features. They recently released the v2.0 update, it's just unparalleled software achievement: https://www.reddit.com/r/headphones/comments/zsjmng/qudelix_5k_v20_update_released/

Here's a bit more info/resources/etc. about the Qudelix 5K Bluetooth amp/DAC dongle as it's often out of stock these days: https://www.reddit.com/r/headphones/comments/zgk4s8/equalizer_apo_doesnt_for_me_best_alternative/izhf43z/ and https://www.reddit.com/r/headphones/comments/zsjmng/qudelix_5k_v20_update_released/j18t8qo/

This thread link talks about the Qudelix 5K, AptX Adaptive dongles, and specifically Apple devices: https://www.reddit.com/r/headphones/comments/zc1znn/qudelix_5k_arent_these_issues_a_big_issue/iyuh35j/